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Portland Bureau of Transportation

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NE 15th Avenue - Fremont to Prescott

Final Project Evaluation
NE 15th Ave Test Project Phase II -
Fremont to Prescott


The Traffic Calming Program (TCP) undertook a Neighborhood Collector test traffic calming project in the Fall of 1993 to address traffic problems identified by residents along NE 15th Ave from Fremont to Prescott. This project is an extension of the first phase testing, south of Fremont. This report will summarize current street conditions and compare them to measurements taken before initiating the project.
NE 15th Avenue is a Neighborhood Collector street which serves a single family residence neighborhood, with some commercial uses at the south end. Fremont, to the south, and Prescott, at the project's north end, are both Neighborhood Collector streets. NE 15th Ave has side walks and curbs. Additionally, there is a hill at the north end between the cross streets Mason and Skidmore.
The purpose of a Neighborhood Collector street is to provide access between lower classification Local Service streets and higher classification streets. The intended character of the traffic on Neighborhood Collector streets is best described as higher volume, low-speed traffic.
A traffic committee, composed of area residents, was formed to propose and evaluate solutions to the negative impacts created by the automobile traffic. The goals developed by the neighborhood traffic committee were as follows:
  1. Reduce the 85th percentile speed along NE 15th Avenue, between Fremont and Prescott, to 30 miles per hour through increased enforcement, roadway modification, and education.
  2. Increase pedestrian, bicycle and automobile safety on NE 15th Avenue by making crossings safer and by reducing vehicle speeds.
  3. Reduce noise, vibrations and air pollution on NE 15th Avenue by reducing traffic speeds and by slowing trucks and busses.


Five 22-foot speed bumps, at 400 to 770 foot spacing, were constructed along the 0.5 mile segment of NE 15th Ave, Fremont to Prescott, between August 1994 and April 1995 by the Bureau of Maintenance. Additionally, two temporary pedestrian refuges were installed, at the cross-streets NE Shaver and NE Failing, in March of 1994, with permanent construction in November of 1996.

Graph 1

Vehicle Speeds

As Graph 1 shows, vehicle speeds, previously concentrated between 32 and 40 mph, have been shifted into the range of 23 to 31 mph. The average 85th percentile vehicle speed before the project was 37 mph and ranged from a low of 33 mph to a high of 40 mph. Since bump construction the average 85th percentile speed is 33.2 mph and ranges from a low of 24 mph (near the bumps) to a high of 35 mph. Prior to installation of the speed bumps 30-40% of drivers exceeded the posted speed limit of 25 mph by 10 mph or more. Since bump construction, 10% of drivers exceed the posted speed limit by 10 mph or more.

Graph 2

Graph 2 illustrates how speeds at various points along the length of the street have changed. Speed reductions are greatest where speed bumps were placed. Also, the smallest reduction in vehicle speeds occurred on the hill between Mason and Skidmore. Even though this location is too steep for placement of a speed bump, vehicle speeds still showed a reduction.

Traffic Volume

Graph 3 shows the distribution of vehicle traffic over the course of a single day. As can be seen, the pattern of automobile traffic has not significantly changed from patterns measured prior to speed bump installation.

Graph 3

Traffic volumes measured before bump construction averaged 7100 vehicles per day (vpd) and varied from 6400 to 7600 vpd. After bump construction volumes averaged 5900 vpd and varied from 4500 to 5100 vpd. This represents an approximate 16 percent reduction in vehicle volumes.
Graphs 4 and 5 show measured traffic volumes on NE 14th and NE 16th Avenues, respectively. Traffic volume on NE 14th prior to construction averaged 367 vpd. The average increase in traffic on NE 14th, since construction on NE 15th, is 85 vehicles. Traffic volume on NE 16th prior to construction averaged 230 vpd. The average increase in traffic on NE 16th, since construction on NE 15th, is 50 vehicles. Both of these volume increases are below the allowable increases for these streets.
Graph 4
Graph 5
Traffic Calming on NE 15th Ave. from Fremont to Prescott has successfully reduced the average 85th percentile speed, and significantly reduced the number of 10 mph over posted speed vehicles. Additionally, the number of vehicles using NE 15th Avenue has decreased by an average of 16 percent, without a large number of those vehicles diverting to the nearby Local Service streets. Finally, two intersections were improved for pedestrians with the addition of pedestrian refuges. Each of these effects, speed reduction, volume reduction and safer pedestrian access, contribute to increasing the safety and livability for the residents and users of NE 15th Avenue, Fremont to Prescott.