Portland State University

How can we use a variety of data-driven speed management strategies to make transportation safer and more efficient for all modes–whether you’re driving, walking or taking transit?

The project was led by Yao Jan Wu, director of the Smart Transportation Lab at the University of Arizona. Co-investigators were Xianfeng Terry Yang of the University of Utah, who researches traffic operations and modeling along with connected automated vehicles, and Sirisha Kothuri of Portland State University, whose research has focused on improving signal timing to better serve pedestrians. Join them on Sept 15, 2021 for a free webinar to learn more.

"We want to improve mobility for all users, be it pedestrians, vehicle drivers or transit riders, and there are different strategies to do this. How do we harness data to drive us to these strategies?" Kothuri said.

Funded by the National Institute for Transportation and Communities (NITC), this multi-university collaboration addressed the question from three angles:

• Wu and his students in Arizona looked at the impact of speed management strategies on conventional roadways...

• Download the Final Report (PDF)
• Download the Guidbook on Signal Control Strategies for Pedestrians (PDF)
• Download the Project Brief (PDF)
• Watch the recording of the Jan 26, 2017 webinar

Pedestrians often have to wait longer than drivers for the light to change. Increased delay for pedestrians can lead to noncompliance, which can have a negative impact on safety. Most planning efforts geared toward those on foot have tended to focus on safety, but pedestrian efficiency is also...

Flashing-yellow-arrow traffic signals offer convenience for drivers by permitting them to turn left after yielding to oncoming traffic. This convenience, OTREC research has found, can come at the expense of safety, especially where the traffic mix includes pedestrians.

OTREC researchers David Hurwitz of Oregon State University and Christopher Monsere of Portland State University examined how driver behaviors affect pedestrian safety at flashing yellow arrows. Their findings show that drivers at these intersections often don’t even look for pedestrians.

This research will be the focus of OTREC’s first live interview-style Webinar May 7. Host Steph Routh of Oregon Walks will interview the researcher-practitioner team, explore real-world applications and take audience questions. The Webinar is free. Details are at this link:

Flashing-yellow-arrow Webinar

Flashing yellow arrows have been replacing other left-turn signals, such as solid green or flashing yellow or red circles, to indicate that drivers may turn after yielding to oncoming traffic. These turns are considered “permissive.” Turns where no conflicting traffic is present, such as those indicated with a green arrow, are “protected” turns. The flashing yellow arrow’s inclusion in the 2009 Manual on Uniform Traffic Control Devices sped up the signal’s adoption to...

Why build bigger when you can get more out of what you already have? That’s a question agencies across the country have considered as they face costly expansions of roadway systems or are unwilling or unable to keep building.

Adaptive signal control technologies offer the promise of reducing congestion, smoothing traffic flow and improving safety on existing roads. The Federal Highway Administration has been holding regional summits about this technology across the country.

Metro hosted one of the summits Dec. 1 at the Intelligent Transportation Systems (ITS) laboratory at Portland State University. Federal Highway Administration ITS specialists Paul Olson and James Colyar gave an overview of the technology, which can:

• Automatically adapt to changes in traffic
• Improve travel time reliability
• Reduce congestion and fuel consumption
• Monitor and respond to gaps in traffic signal operations
• Reduce complaints agencies get about bad signal timing

Adaptive technologies use data from sensors to adjust traffic lights, keeping the green light for as long as conditions warrant. The process updates in a few minutes what traditional signal retiming might accomplish only every few years.

The technology is best suited for arterials that receive variable or unpredictable traffic. On these roads, the signals can improve travel time, emissions and fuel consumption by 10 percent or more. Where signal timing has been...