Final Project Evaluation
The Traffic Calming Program (TCP) undertook a streamlined speed bump project in the Summer of 1997 to address traffic problems identified by residents along NE Morris from 102nd to 111th Drive.
The goal of the project was to enhance street safety and livability by reducing the 85th percentile speed of vehicles using NE Morris closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only devices considered for streets like NE Morris, 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 affecting access. It is not an intended goal to reduce traffic volume on low-volume Local Service Streets.
NE Morris serves a single family residence neighborhood. 102nd Avenue, to the west, is a Neighborhood Collector Major City Local Service street. 111th Drive, at the street segment=s east end, is a Neighborhood Collector street. NE Morris has neither side walks nor curbs.
Residents along NE Morris were invited to an open house August 28, 1997 to review and comment on the proposed speed bump installation. Twenty-three people attended the open house. Those who attended expressed approval for the proposed project. A petition was available at the open house for residents along NE Morris to sign and was circulated after the open house by a local resident. . Petition results were as follows:
Percent of Total
|Yes || |
|No || |
|No Signature || |
| || |
Seven 14-foot speed bumps, at 320 to 400 foot spacing, were constructed along the 0.48 mile length of NE Morris, 102nd to 111th Drive, on June 6, 1998 by the Bureau of Maintenance.
As the graph (over) shows, vehicle speeds, previously peaking between 29 and 31 mph, now peak between 26 to 28 mph. The average 85th percentile vehicle speed before the project was 36.5 mph. Since bump construction the average 85th percentile speed is 28.2 mph and ranges from a low of 24 mph (near the bumps) to a high of 31 mph in the 25 mph zone. Before installation of the speed bumps 72.5% of drivers exceeded the posted speed limit of 25 mph and 21.2% exceeded the limit by 10 mph or more. Since bump construction 33.2% of drivers exceed the posted speed limit and 2.0% exceed the limit by 10 mph or more.
Traffic volumes measured before bump construction averaged 1200 vehicles per day (vpd). After bump construction volumes averaged 1000 vpd and varied from 650 to 1160 vpd. Traffic volumes measured on side streets parallel to NE Morris showed no significant increases from volumes measured before speed bump construction.
Traffic Calming on NE Morris, 102nd to 111th Drive has successfully reduced the average 85th percentile speed closer to the posted speed, enhancing street safety and livability.