Final Project Evaluation
The Traffic Calming Program (TCP) undertook a streamlined speed bump project in the Fall of 1997 to address traffic problems identified by residents along NE Going Street from 42nd to 52nd Avenue.
The goal of the project was to enhance street safety and livability by reducing the 85th percentile speed of vehicles using NE Going Street closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only devices considered for streets like NE Going Street, 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 Going Street serves a single family residence neighborhood. 42nd Avenue, to the west, is a Neighborhood Collector street. 52nd Avenue, at NE Going Street's east end, is a Local Service street. NE Going Street has neither side walks nor curbs its entire length and makes a jog north at NE 47th Avenue. The street ends at 52nd Avenue at a play field for Rigler Elementary School. NE 52nd Avenue had speed bumps constructed on it in 1996.
Open HouseResidents along NE Going Street were invited to an open house December 3, 1997 to review and comment on the proposed speed bump installation. Seven people attended the open house. Most of those who attended expressed approval for the proposed project. One individual expressed a dislike for speed bumps. A petition was available at the open house for residents along NE Going Street to sign and was circulated after the open house by a local resident. Of the 73 households along the street, 54, or 73.9%, signed the petition requesting speed bump installation.
Six 14-foot speed bumps, at 400 to 540 foot spacing, were constructed along the 0.51 mile length of NE Going Street, 42nd to 52nd Avenue, on April 5, 1998 by the Bureau of Maintenance.
Vehicle SpeedsAs the graphs show, vehicle speeds, previously concentrated between 20 and 31 mph, have been shifted into the range of 20 to 22 mph. The average 85th percentile vehicle speed before the project was 31 mph. Since bump construction the average 85th percentile speed is 24.8 mph and ranges from a low of 20 mph (near the bumps) to a high of 27 mph in the 25 mph zone. Before installation of the speed bumps 51.3% of drivers exceeded the posted speed limit of 25 mph and 4.8% exceeded the limit by 10 mph or more. Since bump construction 10.9% of drivers exceed the posted speed limit and 0.3% exceed the limit by 10 mph or more.
Traffic VolumeTraffic volumes measured before bump construction averaged 340 vehicles per day (vpd). After bump construction volumes averaged 300 vpd and varied from 270 to 325 vpd. Traffic volumes measured on side streets parallel to NE Going Street showed no significant increases from volumes measured before speed bump construction.
Traffic Calming on NE Going Street, 42nd to 52nd Avenue has successfully reduced the average 85th percentile speed closer to the posted speed, enhancing street safety and livability.