Highway Design and Safety

Field Analysis of Wood Guardrail Post Decay

Wood guardrail posts can be inspected for decay by using a non-destructive testing technique called stress wave timing (SWT). This project investigated the integrity of wood guardrail posts in strategic locations of Washington state using SWT and then analyzed the data to determine factors that may lead to increased wood decay rates. The researchers determined that high climate index, , a measure of a region’s average annual rainfall and temperature, and poor preservative retention levels were associated with high decay rates. WSDOT will be able to use the results of this project in considering approaches to managing its guardrail assets in the future.

... Read More
A Data-Driven Safety and Operations Assessment of Various Left-Turn Phasing Strategies

Because drivers respond differently to different signal phasing sequences, engineers need to evaluate how drivers interpret the message that each phasing sequence is trying to convey. This research evaluated the safety and operational impacts of different left turn movement treatments at signalized intersections by using crash, video, and survey data. The results should help decision makers select more suitable signal phasing plans under various operational conditions.

... Read More
Evaluation of Motorcyclists’ and Bikers’ Safety on Wet Pavement Markings

Pavement markings such as single and double divider lines, edge lines, crosswalks, and bike lane markings are critical in guiding roadway users. However, pavement markings can also lead to catastrophic crashes for motorcyclists and bikers when they are wet or icy. This study evaluated three different pavement marking materials in dry, wet, and icy conditions, in the laboratory and in the field, to help improve rider safety.

... Read More
Safe Main Street Highways: Analyses of Collisions Involving Pedestrians and Bicyclists in Washington State

What could make main street highways safer for alternative modes such as walking and bicycling? Main street highways (MSHs) are stretches of state highways that also act as main streets for local populations. This study looked at where pedestrian and bicyclist collisions most often occur on MSHs and developed models for estimating socio-economic and environmental predictors of collision locations so that WSDOT and local agencies can improve pedestrian and bicyclist safety measures.

... Read More
Study on Illumination for State Highways

WSDOT currently owns and operates illumination fixtures on state freeways and highways with annual operating costs in millions of dollars. There are several ways that the WSDOT could reduce expenditures on illumination. These include using more efficient lighting technologies, operating illumination more judiciously, and installing fewer luminaires. This project reviewed current public agency illumination standards domestically and internationally. The researchers also conducted a thorough literature review of existing illumination products and their operational and maintenance characteristics, examined illumination control systems, and reviewed illumination spectrum technologies, with an eye toward their service, safety, and sustainability. The results are intended to support WSDOT staff in making design and business decisions regarding illumination installation, maintenance, and operation.

... Read More