First Advisor

Christopher M. Monsere

Term of Graduation

Summer 2021

Date of Publication

9-30-2021

Document Type

Thesis

Degree Name

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

Department

Civil and Environmental Engineering

Language

English

Subjects

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

DOI

10.15760/etd.7681

Physical Description

1 online resource (viii, 67 pages)

Abstract

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.

Rights

© 2021 Frank Boateng Appiah

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

Persistent Identifier

https://archives.pdx.edu/ds/psu/36597

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