First Advisor

Christopher M. Monsere

Term of Graduation

Summer 2021

Date of Publication


Document Type


Degree Name

Master of Science (M.S.) in Civil & Environmental Engineering


Civil and Environmental Engineering




Roads -- Interchanges and intersections -- Oregon -- Portland -- Safety measures, Road markings, Automobile drivers -- Behavior, Cycling -- Safety measures



Physical Description

1 online resource (viii, 67 pages)


The increasing trend in the number of bicycle crashes in the U.S since 2009 has been a major challenge to safety. In 2019, a total of 36,096 people were killed on U.S roadways. A total of 846 (2.3%) of these fatalities were bicyclists and around 75% of the bicycle fatalities occur in urban areas and intersections are common locations of crashes. Many bicycle enhancements such as bike boxes, bicycle signals, curb extensions have been installed to improve safety at signalized intersections. The City of Portland OR experimented with an innovative treatment to improve bicycle crossings at unsignalized crossings. This treatment, termed a high visibility cross-bike, was installed at crossings of neighborhood bicycle greenways with busy roadways. The marking is similar way to a continental pedestrian crosswalk but with green pavement markings rather than white. Although the cross-bike marking does not currently require motorists to yield for bicycles waiting to cross the roadway, it was hypothesized that the presence of the marking would alter motorists yielding behavior towards bicyclists and improve the crossing experience for persons on bicycles. This thesis analyzed empirical data to evaluate the modifications in the rate of motorists yielding behavior at three unsignalized intersections in Portland, Oregon. Three intersections (NE Going and NE 15th Ave, SE Salmon and SE 20th Ave, NE Holman and NE 33rd) were evaluated in before and after experiment. A total of 48 hours of video data was analyzed to produce a sample of 1,840 bicycle crossing events (897 before; 943 after) carried out by 2,219 bicyclists. (1,097 before; 1,122 after). The rates of motorists yielding to bicyclists improved after installing cross-bike markings. The yielding rates at NE Going and NE 15th Ave increased from 48% near side to 91% near side and 61% far side to 95% far side after the markings. SE Salmon and SE 20th Ave also realized a significant increase in motorists yielding rates from 21% to 40% near side and 11% to 33% far side. Trends were similar at NE Holman and NE 33rd with rates improving from 38% to 77% near side and 36% to 82% far side. The changes in driver yielding behavior were all statistically significant. A reduction in bicyclists' wait times at the locations was also observed. Finally, it was noted that the cross-bike marking encouraged bicyclist to position themselves more consistently in the intersection as they waited to cross.


© 2021 Frank Boateng Appiah

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