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Portland Bureau of Transportation

Phone: 503-823-5185

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Humboldt Elementary School

School Safety Project
Final Evaluation
N Gantenbein, N Haight and N Commercial

The Traffic Calming Program (TCP) undertook a School Safety Project (SSP) in the Fall of 1994 on the local streets adjacent to Humbolt Elementary School, N Gantenbein, N Haight and N Commercial.
The goal of a SSP project is to enhance the safety of the younger pedestrians associated with the elementary school by reducing the 85th percentile speed closer to the posted speed limit. Speed bumps are the only device considered for streets like Gantenbein, Haight and Commercial, 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.
Gantenbein, Haight and Commercial serve a single family residence neighborhood. N Skidmore, to the south, is a Neighborhood Collector street. Alberta at the north end, is also a Neighborhood Collector. Gantenbein, Haight and Commercial all have sidewalks and curbs.
Open House

All residents along Gantenbein, Haight and Commercial were invited to an open house held January 17, 1995 to review and comment on the proposed bump installation. None of the residents attended the open house. Only the school principal was present. She expressed her approval for the proposed project. There is no petition or ballot requirement for School Safety Projects as they are a City Council mandated activity.

Four 14-foot speed bumps were constructed along both Gantenbein, and Commercial between Skidmore and Alberta, and two 14-foot speed bumps were constructed on Haight. The Bureau of Maintenance completed construction in June of 1996.
As the graphs shows, vehicle speeds on N Gantenbein N Commercial and N Haight, have been shifted from the 23-34 mph range into the 20-28 mph range.
The 85th percentile vehicle speeds before the project were 31 mph on Gantenbein and Haight, and 32 mph on N Commercial. After bump construction the highest 85th percentile speed measured was 26 mph.
Traffic volume measured when school was in session on N Commercial before bump construction was 790 to 1370 vehicles per day (vpd). After bump construction N Commercial volumes measured 450 vpd. This is a significant reduction in traffic, possibly identifying cut-through traffic that has chosen alternate routes.
Volume on N Haight was measured in September of 1994 at 400 vpd. After bump construction 330 vpd were measured.
On N Gantenbein the volume before construction was 770 vpd. After construction the volume was 570 vpd. Both volumes on N Gantenbein were measured during the school year. No adjacent streets were identified as possible alternative routes since none are continuous from Prescott to Killingsworth.

Traffic Calming on all three of these streets, N Gantenbein, N Haight and N Commercial has successfully reduced the 85th percentile much closer to the posted speed and that, with the reduction in traffic volumes, has greatly enhanced school pedestrian safety.