Fed Government Guidelines for Sidewalks and Trails

Chapter 2. Understanding Sidewalk and Trail Users

In order to meet the needs of a broad group of sidewalk and trail users, designers and engineers must have a true understanding of the wide range of abilities that will occur within the population and how design parameters can influence those abilities. Since people are naturally most comfortable and confident with their own needs and experiences, designers and engineers should attempt to create a connection between themselves and the broad range of people who will use the facilities that they create. A successful understanding between designers and those they are designing for will result in a future of more accessible facilities and higher quality experiences on public sidewalks and trails.

Figure 2-1. Accessible facilities and high quality experiences on sidewalks and trails result from an understanding of the wide range of abilities that exist within the population and how the design process can meet the needs of people of all abilities.

2.1 Function, activity and participation

In 1981, the World Health Organization published the International Classification of Impairment, Disability and Handicap (ICIDH) so that communication and terminology could be standardized and understood on an international level (World Health Organization, 1980). The ICIDH defined three terms for describing health-related restrictions of an individual's level of function:

Impairment - a difference in the way a body is constructed or functions;

Disability - a limitation in the way daily functions in the community can be performed as a result of an impairment; and

Handicap - a limitation of function imposed by the beliefs of the community.

Figure 2-2. This wheelchair user has a mobility impairment that may or may not create a disability depending on the design of his environment.

These definitions highlighted a basic premise that has been the foundation of accessibility issues and concerns during the past two decades:

An impairment is a function of the individual. A disability or handicap occurs because of limitations imposed on the individual by the community in which he or she lives. Thus, disability and handicap are functions of the environment rather than the individual and both are preventable through a combination of education, assistive technology, planning, and design.

Recent revisions to the ICIDH go even further in identifying disability as a function of the environment (World Health Organization, 1999). The new classification system (ICIDH-2) is designed to describe the health status of all individuals, with and without disabilities. The labels of "disability" and "handicap" have been removed from consideration. Using the ICIDH-2, the functional status of each individual can be described using the following dimensions:

Function - the physiological or psychological functions of the body or the anatomical body parts;

Activity - the performance of a task or action by an individual;

Participation - an individual's involvement in life situations within his or her society;

Contextual Factors - environmental and personal factors that impact the individual's functional state.

Using the ICIDH-2, the ability of each individual to use a sidewalk or trail environment can be described through a combination of the these dimensions. In addition, the barriers to sidewalk or trail use that may be encountered can also be described. Each of these dimensions is explained in greater detail in the following pages.

2.1.1 Function

Body functions describe the physiological or psychological functions of the various systems within the human body. Body structures identify the anatomical parts of the body, such as organs or limbs. Body functions and structures are used to describe the functional and structural integrity of all individuals. Impairments are problems in body function or structure.

Figure 2-3. Impairments are problems in body function or structure.

Impairment =Problem in Body Function or Problem in Body Structure

Impairments may be a reduction, loss, addition, or deviation. Impairments can be temporary or permanent, progressive or static, intermittent or continuous, minor or severe. The presence of an impairment does not necessarily indicate the presence of a disease or disorder. Body function or structure can only be changed through interventions that restore the function (such as, a kidney transplant can restore a loss of kidney function) or structure (such as, a bone graft can be used to rebuild a shattered bone). However, an impairment may or may not limit a person's ability to perform activities or participate in society.

2.1.2 Activity

Activity is "what an individual does" (World Health Organization, 1999). It describes a task or action that can be performed by an individual within all aspects of human life. An activity limitation results from difficulties that an individual may have in the performance of an activity. For example, activity is limited when an individual has difficulty performing an activity in the expected manner or is unable to perform the activity at all. The limitation may relate to qualitative or quantitative differences in the way an activity is performed. The following examples demonstrate how activity limitations can be addressed:

Assistive devices - a larger handle can enable someone with limited grip to grasp a toothbrush and brush his/ her teeth;

Personal assistance - a gardener can be hired to look after the exterior home environment if the individual is unable to do so; and

Modifications to the environment - replacing a set of steps with a ramp will enable someone using a wheelchair to enter a building.

Figure 2-4. A powered wheelchair is an example of an assistive device that helps to prevent a mobility impairment from causing an activity limitation.

Although these types of modifications cannot eliminate an impairment, they can be used to eliminate activity limitations.

2.1.3 Participation

Participation refers to the individual's involvement in life situations within his or her community. It describes the individual's degree of involvement, as well as society's response to the individual's level of functioning. Included within the societal context are all of the physical, social, and attitudinal factors that may be encountered. Involvement in life situations has objective and subjective aspects. Objective aspects include being engaged in an area of life, being accepted, or having access to the required resources. Subjective aspects include satisfaction, fulfillment, and enjoyment. Participation differs from activity in that it describes external factors rather than the "internal" abilities of the individual. Participation restrictions describe problems that an individual may encounter when they attempt to be active in life situations. Restrictions may result from the social environment, even when the individual has no impairment or activity restriction. For example, someone who is HIV positive with no symptoms or functional impairment may be denied insurance or excluded from activities because of social attitudes.

2.1.4 Contextual factors

Contextual factors represent the complete background of an individual's life and living (World Health Organization, 1999). They include any environmental or personal factors that have either a positive or negative influence on the individual's function, activity, or participation.

Environmental factors are external to the individual, and include the physical, social, and attitudinal environments that exert an influence on individual functioning. Major categories of environmental factors include:

• Products and technology;
• Natural environments and human changes to the environment;
• Support and relationships;
• Attitudes, values, and beliefs;
• Services; and
• Systems and policies (Gray & Hendershot, 2000).

Personal factors are attributes or features of the individual that are not related to the individual's functional state. These may include factors such as age, gender, educational background, socioeconomic status, personality, fitness, habits, social background, or coping traits.

2.2 Different abilities for sidewalks and trails

People with and without impairments use a variety of methods to travel within their environment. Some people are fit and athletic, others less so. Some people rely primarily on automobiles for travel within their community, while others walk extensively, bicycle, or utilize public transportation. Most people are very familiar and comfortable with the "rules" and expectations for traveling within their community while others may have difficulty understanding or following expected travel patterns. Children and older adults have different physical and cognitive abilities than young adults. People with disabilities often utilize different methods, skills, and abilities than those generally used by people without disabilities. In these and many other ways, each individual is unique.

Figure 2-5. For people who are blind, the use of sidewalks is essential to perform daily living activities. Sidewalks must be designed to meet the needs of all potential users across a full spectrum of abilities.

The range of abilities among our population is also reflected in the wide variety of factors that might affect the use of sidewalks and trails. Whether a particular individual, or group of individuals, can safely and effectively access a sidewalk or trail will depend on a large number of functions, such as:

• Agility
• Balance
• Cognition
• Coordination
• Endurance
• Flexibility
• Hearing
• Problem solving
• Required behavior(s)
• Sensory processing capacity
• Strength
• Vision
• Walking speed

Among any group of individuals, there will be a wide range of abilities for each of the functions that affect the accessibility or usability of the sidewalk or trail. For example, vision is often required to identify signs or directional information that enhance the safety of pedestrians. Vision abilities range along a continuum from 20/20 vision to no vision. Pedestrians using sidewalks and trails may have visual abilities at any point along the continuum. The greater the range of visual abilities that can be accommodated in sidewalk or trail designs, the larger the proportion of people who will be able to safely and effectively travel on the sidewalk or trail.

The ability to participate in community life depends on the ability to travel independently. Virtually every activity that requires people to venture outside of their homes requires the use of pedestrian travel paths, such as sidewalks and trails. Even when relying primarily on automobiles, people still must become pedestrians to get from their automobile into the building or destination. Since the use of sidewalks is essential for performing activities of daily living, such as grocery shopping or errands, access to sidewalks is a right of all individuals. Therefore, it is essential that sidewalk design parameters meet the needs of all potential users across the full spectrum of abilities. Sidewalks are basic to independent living and must meet the highest standards. The use of and access to trails must also be a high priority, particularly for those trails that provide access to essential services and facilities in outdoor environments (such as, visitor facilities and restrooms).

2.3 Designing for all abilities

While function relates solely to the individual, most of the ICIDH-2 dimensions (activity, participation, and contextual factors) are influenced by the society or environment in which the individual lives. All individuals have the right to fully participate in their community. If neighborhoods do not have a safe, comfortable, and convenient pedestrian system, this can leave people isolated in their own homes and unable to participate in everyday activities. Given the broad influence of environmental factors on the individual's level of function, professionals who design or construct sidewalk or trail environments have a significant influence over whether individuals will be able to use and enjoy the sidewalk and trail environments that they create.

Historically, our society believed that the presence of a disability was a function of the attributes of the individual. As such, it was the responsibility of the individual to change or adapt in order to "fit" into the community. For example, if an individual's legs were paralyzed, the individual was expected to find a different way to walk up a flight of stairs and into a building. However, as the ICIDH classification system demonstrates, activity and participation are not just a function of the individual but a reflection of the community environment in which they live. The installation of stairs with no alternate means of access creates activity and participation limitations for those who are unable to walk up the stairs. When a person's independence is denied because of facilities not being accessible, the person, their family, and society pays the cost of their isolation and dependence.

Figure 2-6. Older adults rely on sidewalks to travel within their community to perform daily activities.

2.3.1 The need for a new approach

Sidewalk and trail developers, engineers, and construction personnel build for the future. Since months or years can elapse while a project is developed, designed, and constructed, projects constructed today will not be replaced for many years. Therefore, sidewalk and trail developers must not only be prepared to solve current design problems, but to also be fully aware of how current solutions will meet user demands in the future.

The design of sidewalk and trail environments is important to all pedestrians, but is particularly important to those with activity limitations related to the use of pedestrian environments. Older adults, people with vision impairments, and children frequently rely on sidewalks to travel within their community. People with mobility impairments must also incorporate knowledge of barriers and the location of accessible routes of travel as they plan their participation within the community. For instance, someone using a wheelchair may want to go to the bank, post office, and grocery store. The selection of where to go will be influenced by the accessibility of each facility, as well as the accessibility of the paths of travel between each facility. Barriers along a path of travel may actually force an individual with activity limitations to use different facilities than they would prefer.

Traditionally, the project development, design, and construction of pedestrian facilities have been based on the design characteristics of a "standard pedestrian." Oftentimes the parameters for the "standard pedestrian" were based on a young adult male of "normal" body function and structure. It has always been recognized that these design parameters were meant to represent an average among the population. While these parameters may have been appropriate for pedestrian facilities in the past, the composition of our population has changed significantly in recent decades. Some examples of changes in the population that may affect sidewalk and trail design parameters include:

• There is an increasing proportion of older adults;
• Approximately 20 percent of Americans have a disability and the percentage of people with disabilities is increasing (U.S. Census Bureau, 1994);
• Decreasing mortality rates for a variety of disabling illnesses and injuries are resulting in an increase in the length of time that people live with functional limitations (i.e., people are living longer with less function);
• Over 50 percent of adults in the United States are now obese, making obesity the norm (Center for Disease Control, 1997);
• Many children travel on their own to and from school.

Figure 2-7. Designers and engineers must meet the needs of people of all abilities. Different functional abilities may involve varying walking speeds and endurance.

These changes are expected to continue, and probably accelerate, in the future. Today, even more so than in the past, the concept of the "standard pedestrian" is detrimental rather than helpful in creating high quality pedestrian facilities. In reality, the travel speeds, endurance limits, physical strength, stature, and judgment abilities of pedestrians vary tremendously, and the range of abilities is increasing as our population changes. For example, the average pedestrian as defined in the Manual on Uniform Traffic Control Devices has a walking speed of 1.2 m/s (4 ft/s) (U.S. Department of Transportation, 1988). In contrast, research with older adults indicates an average walking speed of 0.85 m/s (2.8 ft/s) (Staplin, Lococo, Byington, 1998).

Figure 2-8. Signs, marked crosswalks, and crossing guards create accessible sidewalk environments for children who travel on their own to and from school.

Use of a "standard pedestrian" may create unnecessary barriers because the associated design parameters no longer reflect the abilities and needs of our population. In order to meet the needs of our changing population, designers should use the knowledge and awareness of the range of abilities among our population to develop sidewalk and trail environments that do not impose activity or participation limitations because of artificial or unnecessary barriers.

2.3.2 Accessible environments through universal design

Our society now recognizes that everyone has the right to have and use pedestrian facilities. Society's recognition of these rights is supported by legislation prohibiting discrimination, such as the Americans with Disabilities Act, which prohibits discrimination on the basis of disability. Designing sidewalk and trail environments to meet the current and future needs of our changing population requires an inclusive design approach. Building pedestrian facilities now and for the future means beginning to address the needs of a broader range of sidewalk and trail users, including older pedestrians, people with disabilities, and children. Just as roadways are designed to suit the needs of all types of vehicles, sidewalks and trails should be designed to accommodate the needs of all pedestrians (Washington State Department of Transportation, 1997).

Universal design is "an approach to creating environments and products that are usable by all people to the greatest extent possible" (Mace, Hardie & Place, 1991). Instead of designing solutions that benefit only a small target audience (such as, the "standard pedestrian"), universal design emphasizes meeting the needs of all potential users to the greatest extent possible. In addition, universal designs take into consideration the physical, cognitive, emotional, and social changes that each individual experiences over the course of a lifetime.

Universal design encourages and supports the development of facilities that include and are usable by people of all abilities. Providing a ramped entrance to a building at the back door when the front entrance has stairs is not a universal design. Although considered accessible, this solution separates users by their abilities. A universally designed solution would seek to meet the needs of all users by creating access for all through the primary entrance. Successfully addressing the current and future needs of our changing population means incorporating the principles of universal design into all aspects of sidewalk and trail development.

2.3.3 Natural and constructed environmental constraints

The benefits of universal design are not specific to people with disabilities. The key to creating high quality pedestrian environments is to recognize that all individuals have different abilities for using sidewalks and trails. No one is "standard." Everyone has strengths, weaknesses, and differences in abilities along a continuum from very high to very low levels of function. Whether these differences result in an activity or participation limitation depends, in large part, on the demands or constraints found within the sidewalk or trail environment. Activity and participation limitations in sidewalk and trail environments can result from a variety of factors. In general, these factors relate to either the constructed or natural environment. Limitations in the constructed environment are created when built facilities do not meet the needs of users. For example, offices at the top of a tall building would have a tremendous disadvantage for attracting clients if an elevator was not provided. Limitations imposed by the natural environment are not caused by human efforts but may need to be mitigated through human changes. For example, a landslide can make travel along a trail difficult or impossible, particularly for individuals that are not very fit or agile.

The goal of sidewalk and trail design and construction is to ameliorate the constraints within the natural environment and to avoid constraints in the constructed environment to enable effective pedestrian travel. Sidewalk and trail developers should:

• Ensure that the environments that they design and construct do not create activity or participation limitations; and
• Minimize the activity or participation limitations that result from existing natural conditions.

It is only through a universal design approach that activity and participation limitations can be minimized and the barriers within the constructed environment can be eliminated.

2.4 Barriers create activity and participation limitations

Activity and participation limitations can result from an almost limitless range of factors. Within the scope of this guidebook, it is not possible to discuss the full range of potential factors that may result in activity or participation limitations for an individual. Therefore, the following discussion will focus on the most common barriers found within sidewalk and trail environments. In general, the ability of an individual to participate in sidewalk and trail environments is influenced by two types of barriers:

• Movement barriers; and
• Information barriers.

2.4.1 Movement barriers

A movement barrier is anything that restricts an individual's ability to physically move along or within an environment. It may limit the individual's movement from one place to the next (e.g., travel from one side of an intersection to the other), or the ability of the individual to position his or her body within one location (e.g., move the arm and hand in order to use a pedestrian actuated signal device or to get close enough to push it). The movement barrier may create a physical barrier to movement (e.g., soft, unstable surfaces), or it may result in a barrier because of the type of movement the individual is required to perform (e.g., short signal times require rapid analysis and very fast positioning and movement to cross and may not provide enough time for decisionmaking before crossing). Movement barriers result from a variety of factors within the environment and/or the individual.

Movement barriers within the environment can occur in both natural and constructed environments. Examples of movement barriers within the environment include:

• Difficult terrain (e.g., steep slopes or cross slopes and soft, unstable, or uneven surfaces);
• Travel path designs that require high speed movements and/or sudden or frequent changes of direction (e.g., short signal phases that do not provide sufficient crossing time);
• Travel paths without areas for rest or shelter;
• Obstacles within the path of travel (e.g., lamp posts, benches, rocks, railings, or barrier);
• Sidewalk/trail design that exposes the user to potential hazards (e.g., unregulated at-grade crossing of a multi-lane highway);
• Environmental designs that require unusual movements or coordination (e.g., placement of pedestrian actuated signal devices in a location that cannot be accessed by all pedestrians); or
• Over and under passes with stairs or steep ramps.

Movement barriers within the individual are determined by the individual's body function and structure. Examples of movement barriers within an individual are:

• Limited agility (e.g., ability to negotiate obstacles, steps, or curbs);
• Limited endurance (e.g., inability to increase heart rate or breathing, quick onset of fatigue, or increased energy expenditure for ambulation with crutches or canes);
• Limited speed (e.g., limited coordination or lack of strength for quick movements);
• Unpredictable movement patterns (e.g., children often go from "start" to "stop" or may change directions or plans on the spur of the moment); and
• Deliberations in decisionmaking (e.g., people with vision impairments or older pedestrians with cognitive disabilities may take longer to start and determine when to cross).

Table 2-1 provides examples of how some sidewalk and trail users may experience activity or participation limitations because of environmental or individual movement barriers.

Professionals who design or build sidewalk and trail environments should ensure that they:

• Do not create movement barriers within the environment;
• Eliminate or at least minimize the movement barriers that naturally occur within the environment; and
• Design environments that do not impose a barrier that results in movement barriers for an individual; thus creating a disability from an environment that doesn't function (see Table 2-1).

Design recommendations on how to achieve these objectives are discussed in more detail in the Sidewalk Development and Trail Development sections.

2.4.2 Information barriers

Information barriers restrict the individual's ability to use information contained within the sidewalk or trail environment. An information barrier may limit the individual's ability to:

• Recognize or receive information (e.g., a loss of vision and loss of hearing and vision together prevents an individual from utilizing visual signs);
• Understand the information received (e.g., a person with a cognitive impairment may see a flashing "WALK" or a "DON'T WALK" signal but not understand what it means; children have difficulty judging the speed of an approaching vehicle);
• Decide on a course of action quickly (such as, picking a gap), align themselves properly, and start to cross within the signal phase; or
• Act upon the information in the anticipated manner (e.g., young children believe that adults will protect them from harm, so they may ignore a stop sign for pedestrians to stop on trails or shared-use paths, even though they see and understand the sign).

Table 2-1. Movement Barriers

The following table provides examples of how some sidewalk and trail users may experience activity or participation limitations because of environmental or individual movement barriers.

	Environmental Movement Barriers					Individual Movement Barriers
User Description	Difficult terrain	Soft surface	Obstacles	Signal actuation	Complex decisions	Limited agility	Limited endurance	Limited speed	Unpredictable movement patterns
Stroller User	X	X	X			X
Wheelchair User	X	X	X			X	X	X
Inline skater	X	X	X			X			X
Individual with limited balance	X	X	X			X			X
Individual with a vision impairment	X	X			X	X			X
Older adult					X	X	X	X	X
Child	X				X	X		X	X
Individual who is obese	X	X	X					X
Crutch or support cane user	X	X	X			X	X	X
Individual with low fitness levels	X						X	X
Individual with a cognitive impairment				X	X			X	X
Individual with an emotional impairment					X				X

Information barriers may result from factors within the environment and/or the individual. The design of high quality, accessible pedestrian environments includes measures to ensure that information about the environment is available to all pedestrians.

Information barriers within the environment include:

• Limited sight lines;
• Complex paths of travel;
• Inaccessible formats for pedestrian information;
• Ambiguous or unclear signs or signals;
• Information available through only one format (e.g., visual but not auditory);
• Unclear or missing information about the appropriate pedestrian path of travel; and
• Decisions (e.g., selecting a gap)requiring vision.

Figure 2-9. Pictorial symbols are easier for people with cognitive impairments or limited English language skills to understand.

Information barriers for some individuals can also be addressed through the design of the sidewalk or trail environment. Examples of information barriers for some individuals include:

• Limited ability to receive information (e.g., limited vision may prevent a person from receiving visual information, and loss of hearing will prevent a person from receiving auditory information);
• Limited ability to process or understand the information received (e.g., an individual with a brain injury may see a traffic sign but be unable to understand the meaning of the text);
• Limited ability to act in accordance with information received (e.g., a person with an emotional impairment may be so overwhelmed with the desire to get to a different location that they ignore a red light even though it can be seen and understood); and
• Decreased speed for processing information, making decisions, and implementing action (e.g., an individual with a cognitive or vision impairment may require more time to decide that it is safe to cross an intersection and, by then, the conditions may have changed or the light may be red for the pedestrian).

Table 2-2 provides examples of how some sidewalk and trail users may experience activity or participation limitations because of environmental or individual information barriers.

Those who design sidewalk and trail environments must ensure that they:

• Do not create information barriers within the environment;
• Eliminate or at least minimize the information barriers that naturally occur within the environment; and
• Design environments that do not impose a barrier that results in information barriers that occur for specific people thus creating a disability from an environment which doesn't function (see 2.2).

Design recommendations for creating sidewalk and trail environments with information accessible to all pedestrians are discussed in more detail in the Sidewalk Development and Trail Development chapters of this guidebook.

Table 2-2. Information Barriers

The following table provides examples of how some sidewalk and trail users may experience participation limitations because of environmental or individual information barriers.

	Environmental Information Barriers				Individual Information Barriers
User Description	Sight lines	Inaccessible formats	Irregular and skewed intersections	Complex signage	Limited ability to receive	Limited ability to process	Slower speed to process	Limited ability to have an expected response
Individual with a vision impairment	X	X	X		X
Individual with a hearing impairment	X	X	X		X
Individuals with brain injury			X	X	X	X	X	X
Individual with a mobility impairment	X		X					X
Individual with limited English language skills		X		X	X	X	X	X
Older adult			X	X			X	X
Child	X		X	X		X	X	X
Individual with limited concentration abilities			X	X			X	X
Individual with a cognitive impairment		X	X	X		X	X	X
Individual with an emotional impairment			X				X	X

2.5 Conflicting pedestrian needs

All pedestrians will have different needs; therefore, changing a design to enhance access for one group can create additional barriers for other individuals. It must be recognized that it is not possible to create an environment that provides equal levels of accessibility to every individual. However, the goal should be to make all sidewalk and trail environments accessible to the largest possible number of potential users.

In order to create high quality sidewalk and trail environments that are usable by the highest proportion of pedestrians, designers should understand how a user's abilities are impacted either positively or negatively by any given design feature. The following examples illustrate the need for designers to be aware of the impact of design features on all potential users:

• Walking on slopes - A ramp installed to permit access into a building without the use of steps may impede access for someone who has a limited ability to walk on sloped surfaces. People who use walking aids or have limited balance may have greater access via a set of stairs than can be provided if they are required to use a sloped surface, such as a ramp or graded terrain.
• Detection of the sidewalk-to-street transition - Curb ramps are critical access features for people who use wheeled forms of mobility (e.g., wheelchairs, strollers, bicycles, and inline skates). However, they make it much more difficult for people with vision impairments to detect the transition between the sidewalk and the street. It is very difficult to detect differences between gradual slopes in the absence of visual cues. Individuals who have reduced sensory capacity in the extremities experience similar barriers. These problems are enhanced further among individuals with sensory and other impairments (e.g., diabetes can lead to vision and sensory function loss).
• Knowledge of traffic movement - Roundabouts and right turn slip lanes are used to improve intersection efficiency for automobiles. However, they also disrupt the "stop and go" traffic patterns that are typically found at an intersection and force pedestrians to rely on visual cues to identify gaps available for crossing. The traffic sounds that people with vision impairments use to identify the gap for a safe crossing are disrupted or absent when there is a continuous traffic flow. Furthermore, if the traffic does not yield to the pedestrian, problems may be created for people with slower walking speeds and starting times, as well as for those who have difficulty determining the appropriate crossing time or location.
• Different abilities among users on the same path - Along a shared-use path, different user groups may compete for the same space. Differences in factors such as travel speed, type of technology, noise or anticipated experience may create conflicts between users. In addition, when people of different abilities use the same travel space, improving access for one user group may reduce the accessibility provided to other users. Examples of conflicts between users of different abilities include:
  1. Grade reductions through elongated, winding trails to enhance accessibility for pedestrians with movement limitations may decrease the usability and desirability of the trail for cyclists commuting to work who are looking for optimal speed and efficient paths of travel;
  2. Individuals with limited agility may have difficulty avoiding cyclists traveling at higher speeds if cyclists are not easily detected;
  3. Road cyclists and pedestrians generally prefer a firm and stable surface, while runners and equestrians prefer a softer surface; or
  4. Mountain bike riders may prefer a trail with many obstacles while runners, wheelchair users, and road bike riders prefer a smooth trail surface.

When addressing the conflicting needs of users, designers should focus on making improvements to include use of the widest range of potential users. Maximizing use may mean employing additional design tools. For example, a detectable warning (see Chapter 6) located at the bottom of a curb ramp can improve curb ramp detectability by persons with vision impairments. Users traveling at various speeds can be accommodated by splitting shared-use paths to provide separate travel paths for slower users. The needs and capabilities of all potential users should be considered and balanced when designing pedestrian facilities.

Figure 2-10. Some ambulatory pedestrians with mobility impairments benefit from walking aids, such as walkers, to minimize the effects of their impairment.

2.6 Function, activity, participation, and technology

We are living in the "technology and information" age, and technology is constantly and rapidly changing the way we do things. Technology allows us to travel farther and faster, communicate information instantly, and do activities and perform feats that were previously extremely difficult or impossible.

One facet of the technological revolution is the development of assistive technology to enhance function, activity and participation. There is an ever-increasing array of technology available to individuals. Some types of assistive technology, such as the gears on a bicycle, are widely known and understood. Other types of assistive technology, such as the devices used by many individuals with disabilities, are not widely recognized.

While it is not possible for every designer to have detailed knowledge of every type of assistive device, a general understanding of the functions and uses associated with the more common types of assistive technology used by people with impairments is an important factor for enhancing activity and participation.

Assistive technologies play a valuable role in enhancing the ability of people with disabilities to navigate independently through indoor and outdoor environments. These devices can sometimes be used to minimize or eliminate the activity limitations and participation restrictions that exist within sidewalk and trail environments.

The broad range of assistive technologies for people with disabilities is often discussed in terms of a continuum of technologies that include (Axelson, 1988):

• Personal technologies;
• Activity-specific technologies; and
• Environmental technologies.

Figure 2-11. A wheelchair is an example of a personal technology that allows a person with a mobility impairment to accomplish all types of daily activities.

2.6.1 Personal technologies

Personal technologies are things that are closely associated with, and usually connected to, the individual. They include things that you utilize, such as a long white cane, eye glass, wheelchair, or guide dog, as well as things you wear, such as eyeglasses, a hearing aid, or prosthesis. Personal technologies enhance the body's function or structure with the goal of enhancing the individual's ability to accomplish a variety of day-to-day activities.

Personal technologies generally only benefit the owner of the technology, and require the individual or the individual's health care or insurance provider to bear the cost of purchasing and maintaining the device. In addition, each type of technology will have positive and negative aspects. For example:

• A wheelchair provides easy mobility on flat, firm surfaces. However, it is much more difficult to maneuver on slopes. Traversing steps or curbs is extremely difficult if not impossible.
• A missing leg can be replaced with a prosthetic leg. Current technology works quite well if the individual retains his or her own knee. However, a prosthetic leg does not provide the sensory feedback that is needed to ensure stable foot placement, detect obstacles, or maintain balance.
• Eyeglasses are a very common type of technology used to correct mild to moderate vision impairments. However, eyeglasses are cumbersome to use in rain, fog or cold weather conditions, and special "safety" frames are required for sports or activities that might result in impact to the device.
• Individuals with severe vision loss often use a long white cane or guide dog. A long white cane provides advance warning about obstacles on the path ahead, but it is not effective at detecting other visual cues, including obstacles above 685 mm (27 in). Guide dogs can get around obstacles, but their owners must provide instructions and directions as to where they want to travel.
• A hearing aid can be used by individuals who are deaf or hard of hearing to magnify the sounds in their environment. However, the magnification is not selective, so a pedestrian using a hearing aid hears the sounds of traffic and audible pedestrian signal magnified.

Figure 2-12. A long white cane is an example of a personal technology that allows a person with a vision impairment to independently accomplish many daily activities.

2.6.2 Activity-specific technologies

Activity-specific technologies are devices that enhance an individual's ability to perform a specific activity. They include all types of sports equipment (e.g., bicycles and inline skates), equipment for activities of daily living (e.g., pots and pans, toothbrush, and hairbrush), as well as devices designed specifically for one individual (e.g., knee brace and custom ski boots). Activityspecific technologies can also be used to compensate for an impairment.

As with personal technologies, activity-specific technologies often benefit the owner of the technology and require the individual or provider to bear the cost of purchasing and maintaining the device. However, many private and trail organizations make activity-specific technologies available to a broader spectrum of users. For example, Vail Mountain in Colorado rents mountain bikes and mountain-bike wheelchairs.

Figure 2-13. Hand bicycles are an example of an activity-specific technology that allows a person with a mobility impairment to participate in cycling.

The best products work for everyone, but in some instances, activity-specific technologies may need to be modified or new technologies may need to be developed in order to assist people with impairments. For example, most people would use a pair of alpine skis to go skiing. People who are unable to stand could use a sit-ski, mono-ski, or bi-ski, which would allow them to ski while seated. Similarly, bicycles are designed to allow people to travel at greater speeds and distances using human power. People without the use of their legs could use a handbike to perform a cycling activity using only their upper body.

Each type of activityspecific technology will have both positive and negative impacts on the individual's function, activity and participation. For example:

• Hand bicycles allow individuals to participate in cycling activities without the use of their legs, but the small muscles of the arms require a much finer gradation of gearing and current designs require a low seating position with less visibility. Scenic lookout points on multi-use trails often do not take the inability of hand bike riders to walk into consideration.
• A saddle with back supports can enable people with paralysis or limited strength or balance to ride horses. However, they may be unable to dismount during the ride. For example, someone who uses a wheelchair may not be able to dismount and walk while they traverse a steep hill or very narrow trail.
• Biathlon is a combination of cross-country skiing and shooting. Individuals with a vision impairment participate in the target shooting phase by using headphones connected to a laser light that generates audible tones to identify the target.
• Mountain-bike tires make it much easier to ride on unpaved surfaces. However, they also increase the rolling resistance of a bicycle or wheelchair and, therefore, increase the amount of energy that will be needed to pedal or push a given distance.

2.6.3 Environmental technologies and design

Environmental technologies are modifications or designs of a space or environment to increase its usability. Universal design requires the insightful use of environmental technologies to create environments with greater access for everyone. The application of universal design principles focuses on the use of environmental technologies that enhance the participation of users with a broad range of abilities. For example, toilet facilities may be provided on a trail for the comfort of users and protection of the environment. The use of environmental technologies and designs such as a larger clear floor space, accessible door handles, and an at-grade entrance will ensure that the restroom is accessible to a broader spectrum of users.

Examples of sidewalk and trail environmental technologies that benefit individuals with impairments include accessible pedestrian signals, curb ramps, elimination of glare, stabilized trail surfacing, and detectable warnings. The use of environmental technologies and the principles of universal design are the cornerstones for designing high quality pedestrian facilities. Incorporating environmental technologies, particularly those that benefit the broadest spectrum of users, into the sidewalk or trail environment should be every designer's priority.

As with all types of technology, environmental technologies may have a positive or negative impact on a particular user. For example:

• Traditional audible pedestrian signals in the U.S. emit loud tones, bells, buzzes, or bird calls from the pedestrian signal head during the walk interval that are intended to serve as audible beacons to the opposite corner, as well as to indicate the duration of the walk interval to blind pedestrians. The beaconing function of these loud signals has been found to function relatively poorly, and their noise is often annoying to people living and working in the area. Contemporary audible pedestrian signals nearly all respond to ambient sound, so they are much quieter in times of low traffic volume. In addition, the sound source is often at the push button, and it is therefore more localized.
• A ramp may be installed to provide access to a shared-use path constructed on a former railroad bed for people using wheeled forms of mobility (e.g., wheelchair, stroller, or bicycle). However, long ramps are harder to negotiate for people who use crutches or canes, or who have limited balance on sloped surfaces.
• Bulletin boards are often used to convey information to users at the trailhead. However, posting documents with regular size print makes it difficult for people with low vision or people standing at a distance to read the information. Similar problems may be encountered by individuals with limited English language skills (e.g., people who do not speak English or people with cognitive impairments) if the written language is very complex.

Figure 2-14. Curb ramps in the sidewalk environment provide for an easier transition from the curb to the street for people with mobility impairments, and detectable warnings placed appropriately at the bottom of the ramp aid people with visual impairments in recognizing the transition from the sidewalk to the street.

2.6.4 How does technology influence design?

In order to design high quality, accessible environments, it is necessary to have an understanding of the types of environmental technologies that can be incorporated into the universal design process, and how the use of personal or activity-specific technologies may impact the abilities of the user.

The knowledgeable and thoughtful use of environmental technologies will create pedestrian environments with universal access to people of all abilities. This practice of universal design is increasingly recognized and encouraged to allow all persons, with or without disabilities, to move more freely, independently, and safely in outdoor environments.

Figure 2-15. This manual mountain bike wheelchair, with its longer wheel base, is significantly more effective on rugged terrain than a traditional hospital style manual wheelchair.

The impact of some types of impairment can be mitigated to a certain extent through the use of personal or activity-specific assistive technologies. While it is recognized that an environment can never be fully and independently accessible to every possible user, many pedestrians can utilize personal or activityspecific technologies to enhance their ability to function within the environments that designers create. These types of technology can assist people with impairments to become more independent, however individuals may not have access to these technologies and, therefore, the first priority should always be the use of environmental technologies and the universal design process.

Many types of assistive technologies, such as walking aids, improve mobility but do not eliminate the need to design and construct accessible environments. During the design process, it is helpful to have knowledge about the many types of assistive technologies that could be used on sidewalks and trails. The needs and abilities of each user will vary depending on the performance characteristics of any particular type of technology. The benefits obtained from a particular type of technology will also be influenced by the skill, experience, and ability of the user, as well as the characteristics of the environment. For example, there are a wide variety of wheelchairs for individuals with mobility impairments. The outdoor environment performance characteristics of the traditional, hospital-style manual wheelchair are very different from the mobility that can be achieved using a powered wheelchair specifically designed for rugged, outdoor environments.

Personal, activity-specific, and environmental technologies are interdependent. The choice of a personal, activity-specific, or environmental solution will depend on specific parameters of the barrier, such as its location or availability for public use. For instance, a person who is paralyzed may use a wheelchair as a personal technology. However, to use a sidewalk or shared-use path effectively, environmental modifications, such as curb ramps also need to be provided. If the same person chose to use a more rugged recreation trail, an activity-specific technology, such as a mountain-bike wheelchair might be required. Understanding the interdependent relationship between the environment, the required activity, and the abilities of the person is an important fundamental step in the ability to design effectively for the future.

Selecting a wheel design and technology is a decision based on ability, type of usage, and, often, cost. Manual chairs and power chairs maneuver differently in turns and changes in level. Manual chairs have advantages of being portable, generally smaller, lighter in weight, require less maintenance, and generally cost less. A manual chair allows the person with the upper body ability to stay physically active, but power chairs can be more effective on steeper grades.

2.6.5 Limitations of technology

Despite the tremendous benefits provided by assistive technology, there are major limitations related to the essential use of assistive devices to overcome barriers within the environment.

• The cost of most assistive devices makes them unavailable to many people, especially for the disproportionate number of people who have disabilities that do not have jobs and/or live in poverty;
• Even with the use of the most sophisticated forms of assistive technology, the individual still needs many skills and abilities to have independent mobility in the community. For example, a person who uses a power wheelchair for mobility must have the cognitive and physical abilities to operate the wheelchair safely and effectively;
• The usability of the technology must also be considered. In many cases, existing technology can perform a similar but somewhat different function than the function that has been lost as a result of the impairment. For example, a long white cane can be used to avoid obstacles on a sidewalk, but cannot actually replace the functions of human vision;
• Reliability is also a major factor for consideration. It is relatively unlikely that your legs will suddenly and completely stop functioning. However, a flat tire or a loss of battery power can instantly immobilize some types of technology; and
• Portability is a significant factor for individuals who drive, ride as passengers, or take taxis. Powerchairs weigh hundreds of pounds and do not fold.

For these reasons, and many others, the use of personal or activity-specific assistive technology cannot be assumed and should not be considered to be an alternative to appropriate, high quality, and accessible designs.

I 405 Corridor featured as a Best Practice on FHA website

CASE STUDIES
Washington DOT's Corridor Program

The I-405 Corridor Program was led by Washington State DOT (WSDOT) with four other "co-lead" agencies — FTA, FHWA, King County (representing both King County Metro, the county-wide bus transit operator, and the county highway department), and Sound Transit, the regional transit agency. A formal organization was established, with a three-level committee structure composed of political, citizen and technical (transportation and resource agency) representatives.

The intent was to combine planning for corridor-wide transit and highway improvements with the preparation of a "programmatic" or first-tier EIS meeting requirements both for NEPA and for SEPA (the Washington State Environmental Policy Act). It was understood that the program would result in definition of a "preferred" set of highway and transit "projects." These individual projects could then proceed to project development, including preparation of second-tier, project-level EIS documents as needed and appropriate. The state and federal resource agencies would sign off on the preferred set of projects, but would still be able to comment on the second-tier EIS documents before issuing permits for individual projects later on, when greater design detail was known.

The Corridor Program, now complete, had a specific set of goals including products, time-schedule for completion, and budget, but was undertaken in the context of a longer-term intent to enhance cooperation among transportation and resource agencies in an improved decision-making process.
Map illustration of Washington's I-405 Corridor with a red arrow starting near Edmonds and curving down to the right and ending near Auburn.
Key Features

Challenging corridor. The I-405 Corridor is a 30-mile long, highly developed urban-suburban corridor on either side of the existing I-405 freeway. The I-405 freeway was originally built to the east of Lake Washington to bypass the congested I-5 freeway, which runs through the heart of Seattle on the west side of Lake Washington. The corridor is topographically constrained by Lake Washington, by high and long glacial ridges, and by the urban development already in place. I-405 has some of the highest congestion levels in the state, lasting 8-12 hours per day, and traffic is projected to grow 56% by 2020, driven by densification within the corridor and suburban growth to the east. The corridor passes through two major watersheds and some smaller ones, each with lakes and streams containing fish species recently listed under the Endangered Species Act. There is great public debate about solutions to the congestion, and even more controversy and doubt about funding for possible solutions.

Formal structure to manage the technical Work, public involvement and decision process. Oversight of the I-405 Program work effort was established through a three-level committee structure:
Graphic entitled, 'The Decision-Making Process in the I-405 Corridor Program. Shows four entities, '1. Steering Committee', '2. Citizen Committee', '3. Executive Committee', and '4. The Public'. A detailed description of the graphic occurs in the numbered items in the paragraph below.

1. An "Executive Committee," made up of elected officials from the local jurisdictions and the State Legislature; and meeting about quarterly throughout the three-year process.
2. A "Citizens Committee," composed of appointed individuals representing business, neighborhood and special interest organizations; and meeting about every two months. Many of the individuals on this committee were politically powerful.
3. A "Technical Steering Committee" composed of staff representatives from the five co-lead agencies, local governments in the corridor, and the state and federal resource agencies.

The technical work of preparing alternative long-term programs of highway and transit improvements for the corridor for evaluation by the committees, and preparing the programmatic EIS documents, was accomplished by a combination of WSDOT staff and consultants. This work was overseen at weekly meetings of the Project Management Team, composed of staff representatives from the five co-lead agencies — WSDOT, FTA, FHWA, King County and Sound Transit.

Structured public involvement program. Over the course of the three-year effort, the I-405 Corridor Program conducted 95 formal committee meetings (which were open to the public); held 9 special public meetings, (including open houses and public hearings on the EIS); published and distributed 8 program newsletters to residents of the corridor; had almost 150 speaking engagements with public groups; published news monthly on the program web-site; had more than 100 news stories in the print and broadcast media about the program efforts; conducted a 1200-person public opinion survey; and sent regular program updates to city, neighborhood, business and special interest groups. About 25% of the $7 million budget for consultant services went to public involvement activities.

Environmental goals. In response to the community's strong environmental ethic, broad environmental goals were established to:

* Integrate transportation and environmental (habitat protection) investments;
* Use a watershed-based strategy to achieve the greatest environmental benefit; and
* Support Washington Growth Management Act objectives.

To achieve these goals, the Corridor Program determined that it would need to:

* Work closely with partners from the resource agencies, tribes and local governments;
* Identify environmental resource protection needs and issues;
* Look for opportunities to address/avoid project impacts in advance of construction; and
* Where possible, remedy previous actions having negative impacts on the environment.

In response to those goals, the "preferred alternative" included projects to restore fish habitat in a number of major streams previously hurt by development, as well as inclusion of habitat protection actions as part of any new construction projects.

Multi-modal alternatives. Both transit and highway agencies were involved as co-lead agencies, and a broad range of highway and transit alternatives to meet the corridor's travel needs were explored.

The final set of projects that were selected as the "preferred alternative" included not only construction of 170 new lane-miles of highway, but bus rapid transit (BRT) through the major north-south portion of the corridor, with 11 BRT stations, 400,000 additional annual hours of bus service, completion of the existing planned HOV system on I-405, funding for a transportation demand management (TDM) program, construction of 5000 new park and ride spaces and 6 transit centers, funding of 1700 new van pools, construction of 11 direct access ramps to facilitate bus and HOV access to HOV lanes, and consideration of congestion pricing actions.

Concurrence and consensus points. The I-405 Corridor Program required 24 "concurrence agencies," including the state and federal resource agencies, to formally sign their agreement at three "concurrence" points. Those points were the final Purpose and Need document, the list of alternatives to be included in the EIS, and the preferred alternative and mitigation concept. In addition, all 35 agencies were asked to informally give agreement at another nine "consensus" points, which were typically draft chapters of the EIS, approval to publish the Draft EIS, etc. Not all of the consensus points were approved unanimously.
Starting Point

WSDOT had previously undertaken corridor studies involving alternative highway investment strategies, with some consideration of HOV and transit, and generally in connection with a project-level EIS. However, this was the first effort to truly evaluate alternative long-term, multi-modal transportation investment programs at a programmatic EIS level. This was also the first effort at full partnering with the resource agencies during the corridor planning process, rather than at the project development stage.
Motivation

The primary motivation was to find a way to get decisions made. In a corridor with high and growing congestion levels, great controversy among elected officials and the business community about the best solution, and divided responsibility for decision-making among even the transportation agencies, something different was called for. This corridor includes the high density of downtown Bellevue, with a regional mall and several major high-rise office buildings; the office-park development of Microsoft; the office, commercial and light industrial developments in Redmond, Renton and Kirkland; and some new and growing communities to the east. No agreement existed on how to approach decisions, and when the new Endangered Species Act listings included a number of fish species indigenous to the corridor, another layer of complexity was added. The result was "Reinventing NEPA" in the form of the I-405 Corridor Program.
Accomplishments

In just under three years, the I-405 Corridor Program developed alternative multi-modal investment strategies; evaluated their impacts, costs and feasibility with the resource agencies, local governments and the public; prepared a programmatic EIS; held public hearings and adopted a preferred alternative; established a tentative approach for funding of (some) of the program; reached agreement with the resource agencies, including a new mitigation concept that involves restoration of fish habitat in advance of construction; made commitments to tribal agencies on fishing rights; and achieved a Record of Decision on the first tier EIS.
How Change Was Achieved

WSDOT believes that the formal organization and public involvement was critical to the process. Without that organization and public scrutiny, it would have been more difficult to gain the timely actions and approvals of the 24 "concurrence" organizations and the 35 involved agencies. When faced with the "immense political importance" of the program, agencies assigned the appropriate high-level staff needed to get work done and decisions made.

Another major factor for the resource agencies was the commitment of WSDOT to fund mitigations, not only for the new program, but also for restoration of some key habitat lost in urban development and transportation projects during years past. The opportunity to achieve those benefits eventually outweighed initial concerns that giving concurrence to the total program now would undermine their ability to fairly assess project level EIS documents in the future. The resource agencies also liked the early involvement, and the direct contact with the local government representatives.

Because of the special nature of this program, there is still some question about how much real, long-term change will occur in the transportation agencies, including WSDOT, with resource protection at the forefront during transportation planning. Current funding shortfalls mean that the transportation development programs of most agencies have slowed or stopped, and so it is difficult to gauge how much carry-through (and carryover to other projects) will occur.
Challenges

One of the challenges grew out of the formal organizational structure — there were many complaints by participants about the number of meetings. Some participants, including the resource agencies, complained that it was too time-consuming, too "top-heavy" with meetings, too politicized, and not technically rigorous enough. While granting that there were a lot of meetings, WSDOT felt that the formal organization and the resulting public spotlight is what kept the process moving and ultimately got decisions made. WSDOT also acknowledged that the design level achieved for the program of projects was "less than 1%" but felt that was appropriate for the first tier, programmatic EIS.

Getting unanimous agreement from the resource agencies at the three concurrence points proved to be a major challenge. For example, there was great concern that approval of the program of projects would bias future evaluation of project level environmental analyses. They were also asked to agree to not re-visit any of the concurrences unless there is substantial new information or substantial changes in the program. There were "some white knuckles" for resource agency staff members who had to sign their name with only limited direction/approval from their policy boards (or from their top agency appointed heads, in the case of the federal agencies).
"The costs of delay are enormous! Get the key people, including the resource agencies to the table as early as possible."
Mike Cummings, Environmental Planning Manager
WSDOT
Benefits

Getting decisions on a multi-modal transportation development program for the I-405 Corridor was the major aim, and it was achieved — a great benefit to all of the agencies affected.

Another benefit was the agreement to include habitat protection and other environmental resource protection actions within the overall program, after looking at the needs on an area-wide and programmatic level, well before project level decisions begin.
"The process shouldn't be so politicized that legislators are giving direction before the technical analysis has been completed."
Virginia Gunby, Board Member,
1000 Friends of Washington

Some environmental public interest groups were critical of the I-405 Program process, claiming that WSDOT did not involve them in the way they involved other community members, such as influential business people. They also contended that elected officials on the committees used their position to overrule the resource agency staff, and that the level of technical analysis was insufficient. They were concerned that WSDOT might give only lip service to the follow-on project level environmental documents, and will implement a many projects with only an EA. They feared that the agreements on advance habitat protection would be the first to go due to funding shortfalls.
Lessons Learned

WSDOT asked the formal committee members about their thoughts on the lessons learned, and the members offered the following suggestions:

* Resource agencies would like to see a better balance of early involvement and the draw-down on agency staff time (content and volume). They questioned whether there was value added throughout the entire three-year process. They would like to see agency issues prioritized better.
* Some on the Technical Steering Committee would like to see the concurrence points require only a super-majority, not be unanimous. They also felt that it took too long to get the right people to the table. Top-level involvement and support throughout would have avoided some problems near the end.
* It was strongly suggested that someone to represent the resource agencies sitting on the Project Management Team would have helped communications.

WSDOT staff said:

* Keep it simple
* Do it as fast as you can, so that the people assigned don't change
* Get the right people to the table to begin with
* Personal relationships matter a lot
* Have some fun along the way

Next Steps

The next step for the I-405 Program depends upon the programming of funds for the individual projects, and moving into the project level EIS and design work.

A question remains about the status of the overall approach used in the I-405 Program — will it be applied in a broader way to other transportation planning programs being used by WSDOT and the other agencies? The answer to that question is not clear because of the financial uncertainties currently surrounding the entire WSDOT program.
For further information

Michael Cummings
WSDOT Urban Mobility Office
401 Second Avenue South, Suite 300
Seattle, WA 98104-2887
503-986-6572

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Governor Gregoire Hypes Disaster to sell bridges

Is Gregoire hyping disaster to sell bridges?

By Knute Berger 1/17/07

Gov. Christine Gregoire is eagerly sharing the happy news of her willingness to slap tolls on bridges and highways. She met with Oregon Gov.Ted Kulongoski in Clark County the other day to discuss moving ahead on a $4.2 billion new bridge over the Columbia River on I-5. The feds would pick up most of the tab, but Gregoire is set on imposing tolls. To push her agenda, she's using last summer's Minneapolis bridge collapse to make her case for urgency. Only problem is, it turns out the Minneapolis bridge disaster wasn't a case of aging infrastructure. The National Transportation Safety Board (NTSB) has concluded the problem was a design flaw.

Gregoire's statements on tolling the Columbia will ring bells for anyone listening to her rationales for exploring tolls the SR-520 bridge across Lake Washington. According to the Columbian, Gregoire is not only firm about making the new Columbia span--a key north-south link in the greater Vancouver-Portland area--a toll bridge, but she wants to look at imposing more tolls nearby:

Tolls, Gregoire said, will be a part of the finance package...

“The interesting questions there are: Do we start tolling before we even begin construction on the bridge to make sure the tolls can be lower when it’s ultimately opened? Do we do variable tolling to reduce congestion and give more choices to consumers? Do we have to toll someplace else because we’re going to push traffic in a big way” to other bridges? “In my mind, we are going to toll. How do we toll?”

The current Columbia bridge is considered a "bottleneck," but Gregoire is also raising the specter of safety and disaster. According to The Oregonian:

Gregoire said last summer's collapse of an interstate bridge in Minneapolis was "a wake-up call to this nation."

"The interstate bridges that connect Vancouver and Portland are heavily used and aging, and it is time to replace them in the name of safety as well as economic vitality," she said.

The Minneapolis bridge became the poster child for America's aging infrastructure, but Gregoire may have to look for another example. On Jan. 15, the New York Times reported:

Investigators said Monday that the Interstate 35W bridge in Minneapolis, which collapsed into the Mississippi River on Aug. 1, killing 13, came down because of a flaw in its design.

The designers had specified a metal plate that was too thin to serve as a junction of several girders, investigators say....

The I-35W bridge was of a type called “fracture critical,” meaning that the failure of any major member would cause a collapse, because it had no redundancy. The design is lighter and less expensive to build, but has gradually fallen out of favor with highway departments.

This doesn't mean that infrastructure isn't aging and that it doesn't need additional inspection, repair and possible replacement. But the situation in Minnesota isn't a case of neglected maintenance but likely a case of human error or poor judgement.

The case for bridge replacement can be made without hyping the Minnesota tragedy.

Minneapolis Bridge had been recently passed inspection

August 3, 2007
Minneapolis Bridge Had Passed Inspections
By MATTHEW L. WALD and KENNETH CHANG

The eight-lane bridge in Minneapolis that collapsed on Wednesday had been diligently inspected for years and had always passed, state officials said yesterday.

It did not, however, get stellar grades for its condition.

Additionally, officials said the bridge’s design had been considered outmoded for decades because a single failure of a structural part could bring down the whole bridge. About 11 percent of the nation’s steel bridges, mostly from the 1950s and 1960s, lack the redundant protection to reduce these failures, federal officials said.

Over all, the bridge was rated 4 on a scale of zero to 9, with 9 being perfect and zero requiring a shutdown. An inspection report last year said the supporting structure was in “poor condition,” far from the lowest category. Hundreds of other working bridges are in similar shape, but the report did indicate that the bridge had possible issues that needed to be regularly inspected.

The bridge has been inspected annually since 1993, but independent engineers acknowledged yesterday that there are well-known limits to how useful an inspection can be. Bridges, they said, are prone to a variety of problems, and some are hard to spot. At the Minnesota Department of Transportation, shaken engineers made it clear that they knew something crucial had somehow been overlooked.

“We thought we had done all we could,” said Daniel L. Dorgan, bridge engineer at the department’s bridges division. “Obviously something went terribly wrong.”

On Thursday, the United States Department of Transportation said it had told all states to inspect bridges similar in design and construction to the one that collapsed, or to review inspection reports. The department said there were 756 such bridges.

In 1982, a bridge inspector looked at the Mianus River Bridge in Greenwich, Conn., and did not see the metal-fatigued pin that would break nine months later, collapsing three lanes of Interstate 95 and killing three.

In 1987, a New York Thruway bridge near Amsterdam, N.Y., also had a clean bill of health, but inspectors had never gone underwater into the Schoharie Creek to look at the bridge’s footings, where flood waters had scoured the concrete base. When the footings slipped, the bridge fell. Ten people died.

Today, inspectors use ultrasound to check the pins in bridges similar to the Mianus one, and bridge footings receive much more attention.

"I think bridge inspections are the best they’ve ever been," said David Schulz, director of the Infrastructure Technology Institute at Northwestern University in Chicago.

The cause of the Interstate 35W bridge failure on Wednesday will probably become clear through metallurgical examinations of the wreckage, experts said, but recovering the metal parts will be delayed by the search for human remains and the need to keep investigators safe in the swirling waters of the Mississippi.

The bridge was undergoing repair work this summer, and Mr. Schulz said he would be stunned if the work did not play a major role in the collapse. “It’s too much of a coincidence,” he said.

But Mr. Dorgan said he saw no connection between the repair work, which was taking place mostly on the roadway, and the collapse of the steel support structure far below.

Mr. Dorgan said the bridge was believed to be in good enough shape until 2020, when it was due for either a major overhaul or replacement.

Parts of the bridge were considered structurally deficient because of corroded bearings and tiny metal cracks that had been spotted years ago but were considered stable. The rating of “deficient” is a common one that indicates the need for regular inspection and does not mean the bridge is dangerous, said Thomas D. Everett, a top bridge official with the Federal Highway Administration.

The most visible threat to a bridge is usually corrosion. But metal fatigue — the weakening of steel by the repeated weight of heavy trucks bouncing across the bridge surface — is harder to see. Bridges in northern climates are particularly vulnerable to metal fatigue because steel becomes more brittle and prone to cracking when it is cold.

“A crack is very difficult to observe visually,” said Steven J. Fenves, a guest researcher at the National Institute of Standards and Technology, part of the Commerce Department, and a professor emeritus of civil engineering at Carnegie Mellon University. “There may be paint over it, or maybe many layers of corrosion over it. It may be in an invisible place, in the second plate, not the outermost plate.”

The possibility that metal fatigue could cause a bridge to fail was not even considered by bridge engineers in the 1950s and 1960s, when the Minneapolis bridge was designed and built, Mr. Dorgan said. Research at Lehigh University in the 1970s showed that stresses could be much larger than had been thought. The I-35W bridge, which had been designed according to less rigid standards devised by the American Association of State Highway Officials in 1961, had components that would not be included in a bridge built today.

Fatigue cracks appeared in the approaches to the bridge, but no significant problems were detected in the center span. A study in 2001 by University of Minnesota researchers concluded: “The bridge should not have any problems with fatigue cracking in the foreseeable future.”

In a study completed in 2001 by the Federal Highway Administration, 49 working inspectors from around the country visually examined test bridges in Pennsylvania and West Virginia. The inspectors correctly identified fatigue cracks only 4 percent of the time.

Additional techniques like X-rays, ultrasound, magnetic particles or dye can help identify cracks.

Mark V. Rosenker, chairman of the National Transportation Safety Board, said yesterday that his agency would determine whether the criteria for inspections were adequate. “They may well not be enough,” he said. Or the procedures may be adequate but may not have been followed, he said.

Safety board investigators will use computer modeling to study the failure, Mr. Rosenker said, and will also reconstruct parts of the bridge from the wreckage to determine the cause. The board’s final report could be many months away, he said.