Going Green by Flashing Yellow

November 17, 2011

Worldwide, there is growing recognition and concern surrounding the impacts of human activity on the planet’s ecosystem. A broad spectrum of interests including political leaders, scientists, environmental experts, and individuals are seeking to reduce sources of global warming, and the transportation engineering/planning industry is being called to contribute solutions.

Providing increased efficiencies within existing pavement is a challenge facing many agencies who are at the same time working with constrained budgets. Efficient operation of traffic signals is an area where driver delay and emissions benefits can be realized. Relatively straight-forward activities such as optimizing traffic signal timing and choosing appropriate phasing can be made at both existing and new traffic signals to minimize delay and, in doing so, reduce emissions.

The Flashing Yellow Arrow protected/permissive left-turn (FYA PPLT) signal display is a relatively new traffic control device in the transportation engineering professions’ toolbox. The operational benefits of the FYA display are well documented and the public reception has almost universally been positive. Agencies implementing FYA PPLT control are benefiting from both delay and emissions reductions.

Use of the Flashing Yellow Arrow (FYA) at signalized intersections is a low-cost approach to reducing delay and greenhouse gas emissions. The Portland office of Kittelson & Associates, Inc. hosted a recent presentation that highlighted benefits and considerations supporting the use of FYA protected-permissive left-turn (PPLT) signal control. A brief overview of the FYA PPLT control was presented along with key implementation considerations. Washington County, Oregon’s effort to implement FYA PPLT at 372 locations was profiled through a case study that offers a sampling of the relative delay and greenhouse gas emissions reduction achieved. This information should be of particular interest to agencies exploring use of FYA PPLT control.

Session attendees learned about:

• The difference between Flashing Yellow Arrow (FYA) & green ball indications, as well as design considerations;
• Benefits of converting from Protected to FYA left-turns;
• Lessons learned from the Washington County, Oregon experience;
• Advanced signal control features to make permissive FYA’s safer and smarter;
• Videos and case study discussions on the topic of FYA; and
• Extensive Q&A

A PDF copy of the presentation can be accessed HERE.

Other related resources provided during the presentation include:

Fixing the Yellow Trap
Oregon DOT Traffic Signal Policy and Guidelines
Washington State DOT Traffic Signal Control Design Manual
Washington County, Oregon Public awareness campaign/media outreach
NCHRP Report 493: Evaluation of Traffic Signal Displays for Protected/Permissive Left-Turn Control
NCHRP Web Document 123: Evaluation of the Flashing Yellow Arrow Permissive-Only Left-Turn Indication Field Implementation

If you are interested in more details about this important topic and how it might apply to work you are involved with, you can contact any of the presenters by clicking on their name below to email one of them directly.

In the true spirit of involvement and sharing best practices, we encourage you to post your experience, insight, and questions in the comment section at the end of this post. Let’s keep the sharing going!


About the Presenters


Stacy Shetler, PE
Acting Principal Engineer, Washington County, Oregon

Stacy is an engineer at Washington County, Oregon, who has over 12 years experience in the transportation field. His experiences include adaptive signal timing system implementations such as SCATS and InSync as well as overseeing projects to implement FYA at numerous locations. Stacy commissioned and helped co-develop custom FYA-ped friendly logic that is being implemented on county facilities.

Shaun Quayle, PE
Senior Engineer, Kittelson & Associates, Inc., Portland, Oregon

Shaun is a senior engineer with Kittelson and Associates, Inc., who has over 8 years experience in traffic signal systems and traffic operations. His experiences include signal timing optimization projects in numerous states, including advanced signal applications such as gap-dependent FYA settings, co-development of custom FYA-ped friendly logic, and numerous FYA implementations and evaluations.

Hermanus Steyn, PE
Associate Engineer, Kittelson & Associates, Inc., Portland, Oregon

Hermanus Steyn’s wide range of civil engineering experience over 18 years brings sound engineering judgment to exceptionally large and complex projects. He has experience in a variety of transportation studies, with focus on the conceptual and detailed geometric design of all types of roadways from local streets to freeways. He has developed master plans for road networks, including airport traffic circulation, corridor studies, and access management. In addition, he has prepared final traffic design and roadway plans, special provisions, and cost estimates on engineering projects. He has also conducted traffic impact analyses for a variety of developments that have addressed safety issues, access management, and on-site circulation. In addition, Hermanus serves as a trainer regularly educating other professionals, and has been the co-presenter for the following training sessions; 2-day Geometry Design Course, 2-day Traffic Signal Design Course, 2-day Applied Roundabout Design Course, 1-day Safety Oriented Workshop, and 2-hour Roundabout Workshops.

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