Harold Street Traffic Calming
Source: Pedestrian and Bicycle Information Center (PBIC)
Residents thought that excessive automobile speeds and cut-through traffic along SE Harold Street, a local road, presented conflicts with bicyclists and pedestrians.
SE Harold Street Neighborhood Traffic Management Project Tentative Plan
In 1991, the Traffic Calming Section of the Portland Office of Transportation began a project in - to address community-identified problems along SE Harold Street between 52nd Avenue and 72nd Avenue. Further investigation prompted the expansion of the project to include SE Harold between 72nd Avenue and Foster Road.
The project's goals were to reduce traffic speeds on SE Harold Street; to improve safety for vehicles, bicyclists, and pedestrians, and to reduce non-local traffic volume. Traffic calming strategies would include measures that encouraged slower vehicle speeds, increased pedestrian crossing opportunities, and improved sight distances for drivers, cyclists, and pedestrians alike.
The speed limit on SE Harold is 30 mi/h (48 km/h); however, over the length of the street, SE Harold's 85th percentile speed was measured at 37-40 mi/h (60-64 km/h). The daily traffic volume was measured in the range of 3400 to 4800 vehicles per day, which was considered high for a street like SE Harold. Traffic volume increased toward the east end of the project segment, which was likely due to Foster Road's higher classification and its proximity to I-205.
The volume of traffic, combined with retail uses and pedestrian generators, made the excessive speeds on SE Harold a significant concern. In addition, a large portion of the average daily traffic on SE Harold was believed to be cut-through traffic.
The median island on Harold east of 52nd Avenue slows turning vehicles.
A traffic committee was formed from residents in the surrounding neighborhoods to discuss planning for the project. Input was also gathered through required open houses and ballots from residents and landowners of properties adjacent to the street. Bureau of Traffic Management staff developed several alternatives for strategically locating infrastructure improvements to achieve project goals.
Pedestrian safety countermeasures chosen for SE Harold included one median island to reduce corner cutting and turning speed from SE 52nd, eleven 22 ft speed bumps spaced 300-900 ft apart, and curb extensions at 5 intersections.
The Bureau of Maintenance installed the speed bumps in 1993 and 1994. Copenhagen Utilities and Construction, Inc. constructed the project's median island and curb extensions in 1994, at a cost of approximately $117,000.
Curb extension on Harold Avenue.
Total volumes on SE Harold have decreased from 3,400-4,800 vehicles per day to 2,000-3,500 vehicles per day. Traffic volume increases to the east have not changed since Foster Road and I-205 remain unchanged. An average reduction of 1,600 vehicles per day is a significant reduction of 37 percent. This drop is assumed to be a result of route change by drivers inconvenienced by the speed bumps. However, this level of reduction is unusual and most likely due to the availability of numerous alternative routes. Measurements of traffic volumes show an increase in volume on the streets adjacent to SE Harold, while the total traffic volumes, including Harold, have decreased. None of the adjacent side streets showed an identifiable traffic volume increase exceeding allowable thresholds. While the 85th percentile speed on SE Harold prior to project construction ranged between 37-40 mi/h, measurement since speed bump construction shows an average decrease in the 85th percentile speed of 6 mi/h. The graph above shows that the peak in speeds has shifted from 34-36 mi/h to 28-30 mi/h. The shape of the after curve indicates a concentration of the vehicle speeds. Also, a higher percent of vehicles are now traveling below the posted speed limit, which remained 30 mi/h. An examination of available Department of Motor Vehicle records for the 15 months prior to speed bumps construction showed that the number of reported collisions dropped from 17 to 13 when compared to the 15-month time period after construction. The number of injuries reported in those collisions also dropped from 16 to 8.
A 22 ft speed bump on SE Harold.
Traffic calming on SE Harold has been very successful and neighborhood livability has been enhanced. Whenever the average speeds and volumes of vehicles are reduced, an associated reduction in the number and severity of collisions can be anticipated. Additionally, a reduction in speed allows drivers more time to observe the roadway for conflicts and reduces stopping distances. Fewer drivers using the street creates more and longer gaps for pedestrians to cross.
Scott Batson, P.E.
Portland Bureau of Transportation
1120 SW Fifth Ave., Suite 800
Portland, OR 97204
Phone: (503) 823-5422