Everyone wants to reach their travel destination safely. Safe travel speeds support this goal in two ways:
- Safe speeds lower the risk of crashes
- When crashes occur, safe speeds make it less likely that people are killed or seriously injured
Unsafe speeds are a factor in about half of deadly crashes in Portland. This is why speed is a central focus of the city's Vision Zero Action Plan, which aims to eliminate deaths and serious injuries from Portland streets by 2025.
TWO TYPES OF SPEED LIMITS
- Statutory speed limits are specified in Oregon law (see ORS 811.111). Examples include 25 mph on non-arterial streets in "residence districts" (see 801.430) and 20 mph in "business districts" (see instructions below on identifying arterial streets).
- Non-statutory speed limits are not specified in Oregon law, but are set through a process defined in state law (see ORS 810.180). Non-statutory speed limits are usually higher than statutory speed limits.
What "safe speed" means
In urban places such as Portland, safe speeds must account for people traveling in different ways: walking, driving, using mobility devices, biking and skateboarding. It is important to consider people traveling outside of motor vehicles because they are not protected from the impact of crashes. This is why Portland and other cities refer to people traveling outside of motor vehicles as vulnerable users.
In general, streets with higher speeds should physically separate people driving from other travelers in order to help everyone reach their destination safely.
SW Moody Street shows what separation can look like:
Small changes in speed have big impacts
As people travel faster, the risk of death or serious injury rises dramatically when crashes occur. As noted in Portland's Vision Zero Action Plan and the diagram below, a person walking struck by a person driving 40 mph is eight times more likely to die than one struck by a person driving at 20 mph.
The Oregon Department of Transportation controls speed limits in Oregon. ODOT uses multiple factors to determine speed limits, including crash history, "roadside culture," traffic volumes, and roadway alignment, width and surface.
In order to change a speed limit, the Portland Bureau of Transportation must send a request to ODOT. The request and steps involved depend on the type of speed limit being changed (see table above for definitions):
- Non-statutory speed limit to a statutory speed limit: Usually relatively simple and fast. ODOT may respond to a PBOT request in as little as two weeks.
- Non-statutory speed limit to a different non-statutory speed limit: Requires a study and multiple steps (see flow chart) that includes data collection, site visits, a review of crash data and other analysis.
If many people are driving above a speed limit, ODOT is unlikely to approve a request for a lower speed limit unless there is a history of crashes related to speed. This use of speed data is commonly called the "85th percentile rule." (The Federal Highway Administration offers a detailed guide on this and other speed setting methods.)
In a few cases, PBOT can request a speed limit change without completing the standard ODOT process. PBOT has authority to request statutory speeds as low as 15 mph on alleys and narrow residential streets, 20 mph in business districts and school zones, and 5 mph below any statutory speed limit on low-traffic streets intended for walking and biking, such as neighborhood greenways (see ORS 810.180.10 for details). PBOT only has this authority if a non-statutory speed is not in place for a street.
For more details on ODOT's role in setting speeds, refer to the brochure below and the flow chart.
Alternative process streamlines certain changes to speed limits
PBOT has worked with ODOT to obtain permission to use an alternative method to investigate streets for new speed limits. This method, implemented in late 2016, allows PBOT to request new non-statutory speeds using less staff time. The new speed request process also places greater emphasis on vulnerable users and the risk of a future crash.
Under the alternative process, PBOT uses the following general guidelines when requesting new speed limits on eligible streets:
- 40 mph maximum on streets without a center median barrier and edge clear zone, and where people walking and biking are physically protected.
- 30 mph maximum on streets with busy intersections experiencing high crashes, on streets with sidewalks or shoulders next to travel lanes, and on streets with bike lanes next to motor vehicle lanes.
- 20 mph maximum on shared space streets (driving, biking and walking) that do not meet school, business or neighborhood greenways statute for 20 mph.
The alternative guidelines do not apply to federally classified arterial streets and highways, or on any other streets with speed limits less than 25 mph. Unless state law changes, PBOT must continue to use the standard ODOT method to request new speed limits on federally classified arterial streets and highways.
Streets that are eligible for changes under the alternative request process (shown in orange):
You can view a map of these streets through ODOT's map tool:
- Go to http://gis.odot.state.or.us/transgis/
- In the layer catalog on the left, select "classifications"
- Under classifications, select "Federal Functional Class - State" and "Federal Functional Class - Non-State"
- Click "apply"
- Zoom to Portland. Click "legend." Streets that must use the standard ODOT speed limit request process include all interstates and arterials, except for segments located in business districts.
Many ways to support safe speeds
The City of Portland standard is to design streets and street retrofits to the posted speed limit to ensure that all design elements of the street convey to drivers the appropriate speed. This is different from a traditional approach of designing streets to actual auto speeds, regardless of the posted speed limit.
In addition to signage, PBOT has many street design tools available to align speed limits with actual motor vehicle travel speeds. These tools include lane widths, traffic signal timing, curb extensions, roadside landscaping and allowing curbside parking. In addition, police officers and speed safety cameras help align speed limits with actual travel speeds.
Portland's 2016 Vision Zero Action Plan includes three actions to support safe speeds:
- Pilot speed safety cameras on four high crash corridors in the first two years; expand program to additional high crash corridors following the pilot
- Gain local authority for speed reduction on City of Portland streets; prioritize setting safe speed limits in the High Crash Network
- Improve street design to support safe speeds in conjunction with posted speed reduction on four to six streets (not including SD.1 improvements) annually in the High Crash Network, prioritizing improvements in and engaging with Communities of Concern
PBOT will track and report progress on Vision Zero actions and results on an annual basis.