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Portland Bureau of Transportation

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N Bryant - Greeley to Denver

Final Project Evaluation

Introduction

The Traffic Calming Program (TCP) undertook a streamlined speed bump project in the summer of 1996 to address traffic problems identified by residents along N Bryant from Greeley to Denver.
 
The goal of the project was to enhance street safety and livability by reducing the 85th percentile speed of vehicles using N Bryant closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only devices considered for streets like N Bryant, which are classified as Local Service Streets, are not transit or primary fire response routes and have vehicle volumes between 400 and 1700 vehicles per day. Speed bumps have proven to be effective tools to reduce vehicle speed without impacting access. It is not an intended goal to reduce traffic volume on low-volume Local Service Streets.
 
N Bryant serves a single family residence neighborhood and is adjacent to Chief Joseph Elementary School and Arbor Lodge Park. Greeley, to the west, is a Local Service street. Denver, at N Bryant's east end, is a Neighborhood Collector street. N Bryant has sidewalks and curbs.

Open House

All residents along N Bryant were invited to an open house August 20, 1996 to review and comment on the proposed speed bump installation. Six people attended the open house. A petition was available at the open house for residents along N Bryant to sign and was circulated after the open house by a local resident. Of the 25 households along the street, 19, or 76.0%, signed the petition requesting speed bump installation.

Performance

Six 14-foot speed bumps, at 300 to 450 foot spacing, were constructed along the 0.39 mile stretch of N Bryant, Greeley to Denver, September 21, 1996 by the Bureau of Maintenance.
 
 
As the graph shows, vehicle speeds, previously concentrated between 23 and 31 mph, have been shifted into the range of 20 to 25 mph. The 85th percentile vehicle speed before the project was 31.7 mph. After bump construction the average 85th percentile speed is 24 mph and ranges from a low of 21 mph (near the bumps) to a high of 28 mph.
 
Traffic volumes measured before bump construction were 890-990 vehicles per day (vpd). After bump construction volumes averaged 750 vpd and ranged from 670-880 vpd. Traffic volumes measured on parallel side streets adjacent to N Bryant showed no significant increases from measured volumes prior to speed bump construction.
 
Traffic Calming on N Bryant, Greeley to Denver has successfully reduced the 85th percentile closer to the posted speed and enhanced street safety and livability.