The Traffic Calming Program (TCP) undertook a project in the Winter of 1995 to address traffic problems identified on NE Hassalo Street between 55th and 57th Avenues in conjunction with a project on NE 57th Avenue, Halsey to Hassalo. NE Hassalo and 57th form an L-shaped roadway which is one path for traffic.
The goal of the project was to enhance street safety by reducing the 85th percentile speed of vehicles using NE Hassalo closer to the legal maximum speed limit of 25 miles per hour (mph). Speed bumps are the only device considered for streets like NE Hassalo, 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.
NE Hassalo serves a light industrial complex on its South side and Normandale Park on the North. NE Hassalo Street is bounded by NE 55th to the West and NE 57th to the East. Both are Local Service Streets. A significant percent of the daily traffic on NE Hassalo is believed to be cut-through traffic. Additionally the park has a ball field and is heavily used during spring and summer.
All residents along NE 57th were invited to an open house February 28, 1995 to review and comment on the proposed speed bump installation. Seven households were represented at the open house. The majority of those who attended expressed approval for the proposed project. There was concern expressed about the noise generated by the bumps. The businesses along NE Hassalo were contacted by letter explaining the project to be constructed on NE 57th Avenue and asked to provide any comment on the proposal to include NE Hassalo. No comments were received from any of the local businesses, but the Parks Bureau did express support for the installation.
Two 14-foot speed bumps, at approximately 350 feet apart, were constructed along the 0.12 mile stretch of NE Hassalo in June of 1995 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 17 to 25 mph. The 85th percentile vehicle speed before the project was 30 mph. After bump construction the average 85th percentile speed was 23.8 mph and ranged from a low of 21 mph (near the bumps) to a high of 26 mph.
Traffic volumes measured before bump construction ranged from 1100-1200 vehicles per day (vpd). After bump construction volumes measured 1100 vpd. Adjacent streets that were identified as unwanted diversion routes showed no significant increases in traffic volume.
Traffic Calming on NE Hassalo Street has successfully reduced the 85th percentile closer to the posted speed and enhanced street safety and livability.