The Traffic Calming Program (TCP) undertook a streamlined speed bump project in the Spring of 1996 to address traffic problems identified by residents along SE 94th Avenue from Burnside to Stark.
The goal of the project was to enhance street safety and livability by reducing the 85th percentile speed of vehicles using SE 94th Avenue closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only device considered for streets like SE 94th Avenue, 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.
SE 94th Avenue serves a single family residence neighborhood. Burnside, to the north, is a Neighborhood Collector street. Stark, at SE 94th Avenue's south end, is a District Collector street. SE 94th Avenue has neither sidewalks or curbs. A portion of the daily traffic on SE 94th Avenue is believed to be cut-through traffic due to traffic congestion on Burnside and a nearby I-205 on ramp.
All residents along SE 94th Avenue were invited to an open house June 18, 1996 to review and comment on the proposed speed bump installation. Seven households were represented at the open house. Those who attended expressed approval for the proposed project. A petition was available at the open house for residents along SE 94th Avenue to sign and was circulated after the open house by a local resident. Of the 39 households along the street, 31, or 79.5%, signed the petition requesting speed bump installation.
Three 14-foot speed bumps, at 430 to 450 foot spacing, were constructed along the 0.24 mile stretch of SE 94th Avenue, Burnside to Stark, on August 18, 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 28 mph. The average 85th percentile vehicle speed before the project was 33.3 mph. After bump construction the average 85th percentile speed is 24.4 mph and ranges from a low of 19 mph (near the bumps) to a high of 30 mph.
Traffic volumes measured before bump construction were 500 vehicles per day (vpd). After bump construction volumes measured 530 vpd. Traffic volumes measured on side streets adjacent to SE 94th Avenue showed no significant increases from volumes measured prior to speed bump construction.
Traffic Calming on SE 94th Avenue, Burnside to Stark has successfully reduced the 85th percentile closer to the posted speed and enhanced street safety and livability.