The Traffic Calming Program (TCP) undertook a streamlined speed bump project in the summer of 1996 to address traffic problems identified by residents along SE 44th Avenue from Steele to Woodstock Street.
The goal of the project was to enhance street safety and livability by reducing the 85th percentile speed of vehicles using SE 44th Avenue closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only devices considered for streets like SE 44th 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 44th Avenue serves a single family residence neighborhood. Steele, to the north, and Woodstock, at SE 44th Avenue's south end, are both Neighborhood Collector streets. SE 44th Avenue has full sidewalks and curbs, and has stop signs at SE Ellis and Ramona. A large portion of the daily traffic on SE 44th Avenue is believed to be cut-through traffic due to commercial land uses in the southern most two blocks, between Ramona and Woodstock.
All residents along SE 44th Avenue were invited to an open house September 5, 1996 to review and comment on the proposed speed bump installation. Nine households were represented at the open house. The majority of those who attended expressed approval for the proposed project. There was concern expressed about increases in noise. A petition was available at the open house for residents along SE 44th Avenue to sign and was circulated after the open house by a local resident. Of the 40 households along the street, 30, or 75%, signed the petition requesting speed bump installation.
Three 14-foot speed bumps, at 450 to 600 foot spacing, were constructed along the 0.27 mile stretch of SE 44th Avenue, Steele to Ramona Street, on October 5, 1996 by the Bureau of Maintenance. Speed bumps are not generally placed in commercial areas.
As the graph shows, vehicle speeds, previously concentrated between 20 and 28 mph, have been shifted into the range of 17 to 25 mph. The average 85th percentile vehicle speed before the project was 30 mph. After bump construction the average 85th percentile speed is 22 mph and ranges from a low of 20 mph (near the bumps) to a high of 25 mph.
Traffic volumes measured before bump construction were 780-900 vehicles per day (vpd). After bump construction volumes measured 530-600 vpd. The traffic volumes are expected to slightly increase again after speed bumps are constructed on SE 46th this summer and additional volume counts will be taken on all surrounding streets after that work is complete.
Traffic volumes measured on SE 43rd Avenue have decreased. Traffic volumes on SE 45th have exceeded established thresholds for diversion mitigation. Traffic volumes on SE 45th will be checked again after bump construction on SE 46th to check if the diversion is continuing. Traffic volumes on SE 46th increased as expected since speed bumps were not yet constructed on SE 46th when counts on SE 44th were taken.
Traffic Calming on SE 44th Avenue, Steele to Woodstock Street has successfully reduced the 85th percentile closer to the posted speed and enhanced street safety and livability.