National Institute for Transportation and Communities

Researchers Jennifer Dill, Jiahui Ma, Nathan McNeil, Joseph Broach and John MacArthur of Portland State University have published a new article in the November 2022 issue of Transportation Part D: Transport and Environment. The open-access article, "Factors influencing bike share among underserved populations: Evidence from three U.S. cities," examines bike share use and interest among lower-income residents and people of color in New York, Chicago, and Philadelphia.

There is evidence that lower-income and people of color (POC) in the U.S. do not use bike share as much as higher-income and white people. Using data from residents living near bike share stations in New York, Chicago, and Philadelphia, the paper examines reasons for these disparities. Researchers looked at many factors that might explain bike share use and interest in lower-income, racially diverse, traditionally underserved neighborhoods. They focused on residents who live near bike share stations, so that proximity would not be a barrier.

A few key findings:

1. People who are not members, but are interested in using bike share, including POC, are motivated to use bike share for fun, recreation, and social reasons (as opposed to utility).
2. Knowledge of bike share and receiving information from interactive sources (for example,...

Travel time reliability – or the consistency and dependability of travel times from day to day, and at different times of day – is a key metric that significantly affects people’s travel behavior. Since businesses rely heavily on transportation systems, an unreliable transportation network can also impact the economic competitiveness of urban areas. As such, reliable travel times are important for transportation agencies to promote economic stability within a community. Having accurate methods to evaluate reliability is important for both transportation practitioners and researchers.

A new report from Portland State University offers an improved method for determining the confidence interval of travel time reliability metrics. Researchers Avinash Unnikrishnan, Subhash Kochar and Miguel Figliozzi of PSU’s Maseeh College of Engineering and Computer Science used a highway corridor in Portland, Oregon as a case study to evaluate their method, and found that it compared favorably with other methods of evaluating the confidence interval of travel time reliability metrics.

"Traffic engineers can apply this method to come up with a range of estimates for the unknown true travel time reliability metric. The travel time reliability metrics calculated by traffic engineers and transportation planners will have variability due to factors such as road...

The Transportation Undergraduate Research Fellowship (TURF) program at Portland State University has hosted twenty-four fellows since 2017, and recently wrapped up its summer 2022 session. This year, six undergraduate researchers worked on projects aimed at improving the safety and efficiency of multimodal transportation systems. The research goals ranged from surveying pedestrian count programs and safety performance functions across the country, to reviewing case studies of tactical curb extensions and collecting pedestrian data at intersections. 

Hosted by PSU’s Transportation Research and Education Center (TREC), the TURF fellows also experience a variety of workshops with PSU faculty and staff on research, communication and data science skills. They attended the 2022 Forth Mobility Roadmap Conference in June, and participated in networking events with the Portland chapters of YPT and WTS. Here is some of what the students had to say about the experience:

"I enjoyed all of the experiences surrounding my time here at TREC, but I loved the workshops. I especially enjoyed Dr. Golub's workshop...

In order to make sure bicyclists' needs are considered when improving a transportation system, planners and engineers need to know how many people are biking, and where. 

Traditional bicycle counters can provide data for limited sections of the bike network; often these counters are installed at important locations like trails or bridges. While limited in location, they count everyone who bikes by. Meanwhile, GPS & mobile data cover the entire transportation network, but that data only represents those travelers who are using smartphones or GPS. Combining the traditional location-based data sources with this new, crowdsourced data could offer better accuracy than any could provide alone. 

"Knowing how many people are bicycling on a street is really important for a number of reasons. As just a few examples, bicycle volumes give you a way to understand safety data and determine crash rates. They provide insight into where and how bicycle trips are taking place, which can help plan for new or improved facilities," said Nathan McNeil of Portland State University.

Supported by a pooled fund grant administered by the National Institute for Transportation and Communities (NITC), Dr. Sirisha Kothuri of Portland State University led a research project aimed at fusing traditional and...