The phrase,'Unsound Transit', was coined by the Wall Street Journal to describe Seattle where,"Light Rail Madness eats billions that could otherwise be devoted to truly efficient transportation technologies." The Puget Sound's traffic congestion is a growing cancer on the region's prosperity. This website, captures news and expert opinion about ways to address the crisis. This is not a blog, but a knowledge base, which collects the best articles and presents them in a searchable format. My goal is to arm residents with knowledge so they can champion fact-based, rather than emotional, solutions.


Monday, March 10, 2008

WS DOT Traffic Signal Coordination projects in Vancouver

Vancouver Area Smart Trek
Initiative 5
Traffic Signal System

The existing traffic signal systems in the Vancouver area, while functional, will not continue to meet the growing needs of the signal system operators and local residents. WSDOT, Clark County, and the Cities of Vancouver and Camas all operate traffic signals within the project area. Between these four agencies, there are seven different types of traffic signal controllers in use and four different remote monitoring systems used to communicate to the traffic signal controllers. The majority of traffic signals in the region do not have a communications link back to any of the agency headquarters, therefore when a change needs to be made to a timing parameter, a technician must go to each signal location in the field.

On most of the major corridors in the region, the local agencies are using either time-of-day or in a few locations, traffic responsive signal coordination to improve the progression of traffic through these corridors. The City of Vancouver is in the process of deploying Adaptive Signal Timing on a 1.5 mile section of Mill Plain Boulevard between SE 104th Avenue and Hearthwood (12 traffic signals).

Based on input from stakeholders and through workshops, the following traffic signal system needs have been identified:

* Improved monitoring and control capabilities for traffic signals.
* Control and monitoring of traffic signals across jurisdictional boundaries.
* Upgrade pretimed signals to actuated.
* Improved signal coordination for key corridors in the region.
* Improved signal coordination across agency boundaries.
* Compatible traffic signal equipment amongst all agencies.
* Automated signal timing records database.


The following list presents measures that can be used to evaluate traffic signal system projects. The list includes both qualitative and quantifiable measures. Evaluations of performance need not quantify every measure in this list.

Video cameras can be located at critical highway locations to verify road conditions and incidents. Images from the cameras may be posted on a web page and shared with local television stations.

* Number of stops
* Travel time savings
* Emissions savings
* Gallons of fuel consumed
* Vehicle hours of delay
* Integration of signal systems
* Information gathering costs
* Signal system operating costs


Upgrade controllers to “Advanced Traffic Controllers”.
Older types of traffic signal controllers have limited operational capabilities. New microprocessor based Advanced Traffic Controllers (ATC) must be installed to take advantage of new features such as transit signal priority and adaptive signal timing.

Install traffic signal monitoring system for each local agency.
There are four different traffic signal management systems in use between Clark County, the City of Vancouver and WSDOT and a large portion of existing traffic signals do not currently communicate to these systems. To improve the efficiency and functionality of their signal systems, each agency must upgrade their existing systems or purchase new systems in order to obtain the capability to communicate with each type of controller they have in the field.

Obtain/Develop unified traffic signal management system for communicating to multiple types of existing/new controllers.
Currently, each agency has multiple brands of controllers in use. The agencies that have the ability to communicate to their local controllers are using different traffic signal management software programs to communicate to each different type of controller. Through this strategy, each agency will be provided with a signal management program that can communicate to any type of controller they are using.

Work with new NTCIP Center-to-Center protocol to communicate between existing signal management systems.
Update the existing signal systems to meet new NTCIP protocols for Center-to-Center communications. A standard interface can be implemented to allow each agency to share data and resources with other agencies in the region. With this protocol each agency will not have to use the same signal management system.

Expand the use of signal interconnect throughout the region.
Twisted wire pair and fiber optic signal interconnect are currently used to allow local traffic signal controllers to communicate to field masters or to a central monitoring and/or control system. With a physical communication link to traffic signals, agency personnel can upload and download data from a remote site, alarms can alert operators of problems, and timings can be monitored and adjusted.

Deploy Closed Circuit Television (CCTV) cameras.
With this strategy, CCTV cameras would be installed on the major corridors throughout the region where advanced traffic signal system equipment was being operated. Fixed or pan/tilt/zoom cameras could be used to monitor traffic conditions on these roadways, collect counts, and to observe the operation of signal coordination on the corridor.

Implement Traffic Responsive Signal Timing on major corridors within the region.
Traffic responsive signal timing (TRPS) would be used to adjust signal timings based on current volumes. Count stations are used to monitor traffic volumes. When the volumes reach a pre-defined level for a certain amount of time, the coordination plan is changed. Each coordination plan used is predefined, whereas with adaptive signal timing the plans are continuously being modified.

Adaptive signal timing automatically adjusts signal timings in real-time based on current traffic conditions.

Install additional vehicle detection/count stations.
Additional vehicle detection will have the following uses:

* Adaptive or traffic responsive signal timing requires additional vehicle detection: The use of an advanced form of signal timing will significantly improve the efficiency of the roadway.
* Collection of real-time congestion information for local roadways: This information could be displayed on a region wide map that could be accessed through the web or shared with local traffic reporters.
* Collection of historic volume, speed and/or occupancy data. This data can be used for transportation planning in the region and improving signal timing.

Implement adaptive signal timing on selected corridors within the region.
Adaptive signal timing automatically adjusts signal timings (cycle lengths, splits, offsets) in real-time based on current traffic conditions. Adaptive timing has been shown to improve travel times, reduce stops and reduce fuel consumption compared to traditional signal timing methods. Adaptive timing requires additional detection and a communications controller on the selected corridors, as well as a central computer.

The articles are posted solely for educational purposes to raise awareness of transportation issues. I claim no authorship, nor do I profit from this website. Where known, all original authors and/or source publisher have been noted in the post. As this is a knowledge base, rather than a blog, I have reproduced the articles in full to allow for complete reader understanding and allow for comprehensive text searching...see custom google search engine at the top of the page. If you have concerns about the inclusion of a specific article, please email for a speedy resolution.