Final Project Evaluation
The Traffic Calming Program (TCP) undertook a streamlined speed bump project in the Summer of 1996 to address traffic problems identified by residents along NE Fargo from 111th Drive to 117th Avenue.
The goal of the project was to enhance street safety by reducing the 85th percentile speed of vehicles using NE Fargo closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only devices considered for streets like NE Fargo, 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 are 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 Fargo, 111th Drive to 117th Avenue, serves a single family residence neighborhood. 111th Drive, to the west, and 117th Avenue, at NE Fargo's east end, are both Neighborhood Collector streets. NE Fargo has neither sidewalks nor curbs. A large portion of the daily traffic on NE Fargo is believed to be neighborhood cut-through traffic due to a freeway off-ramp at 103rd and Fargo.
All residents along NE Fargo were invited to an open house September 9-11, 1996 to review and comment on the proposed speed bump installation. Seven households were represented during the open house. Those who attended expressed approval for the proposed project. There was concern expressed about the condition of the current roadway and the possibility of driving around the bumps. A petition was available at the open house for residents along NE Fargo to sign and was circulated after the open house by a local resident. Of the 40 households along the street, 33, or 82.5%, signed the petition requesting speed bump installation.
Three 14-foot speed bumps, at 400 to 480 foot spacing, were constructed along the 0.24 mile stretch of NE Fargo, 111th Drive to 117th Avenue, on May 18, 1997 by the Bureau of Maintenance.
As the graph shows, vehicle speeds, previously spread between 23 and 31 mph, have been shifted into the range of 17 to 25 mph. The 85th percentile vehicle speed before the project was 34 mph. After bump construction the average 85th percentile speed is 25 mph and ranges from a low of 22 mph (near the bumps) to a high of 26 mph. Before installation of the speed bumps 64% of drivers exceeded the posted speed limit of 25 mph and 12% exceeded the limit by 10 mph or more. Since bump construction 16% of drivers exceed the posted speed limit and 0.7% exceed the limit by 10 mph or more.
Traffic volumes measured before bump construction was 620 vehicles per day (vpd). After bump construction volumes average 500 vpd. Traffic volumes measured on side streets adjacent to NE Fargo showed no significant increases from volumes before speed bump construction.
Traffic Calming on NE Fargo, 111th Drive to 117th Avenue has successfully reduced the 85th percentile closer to the posted speed and enhanced street safety and livability.