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 focus of the city's Vision Zero Action Plan, which aims to eliminate deaths and serious injuries from Portland streets.
Small changes in speed have big impacts
As people travel faster, the risk of death or serious injury rises dramatically. The diagram below show that a pedestrian struck by a person driving 40 mph is eight times more likely to die than one struck by a person driving at 20 mph.
What makes a 'safe speed'
In urban places such as Portland, safe speeds must account for people traveling in different ways: walking, driving, using mobility devices, biking, skateboarding, etc.
It is important to consider people traveling outside of motor vehicles because they are not protected from the impact of crashes.
PBOT uses the following principles to identify safe speed limits:
- Less physical separation between people driving and vulnerable users requires a lower speed limit. Sidewalks and protected bike lanes are examples of physical separation (see photo below).
- Injury crashes are an indicator that speed limits may be too high
- PBOT may request speed limit reductions even when street design stays the same. While street design can help people drive at safe speeds, studies (such as this one) indicate that adjustments to speed limits alone can still support safety.
- Setting urban speed limits based on 85th percentile speeds is not supported by evidence and is not part of PBOT practice. The 85th percentile is the speed at which 85 percent of people drive at or below on a street.
SW Moody Avenue uses physical separation to help keep people safe.
4 ways PBOT can request speed limit changes
In order to change a speed limit, the Portland Bureau of Transportation must send a request to the Oregon Department of Transportation. The request and steps involved depend on the type of street and the desired speed limit:
|Request type||Eligible streets||Details and examples|
|1. "Alternative"||Non-arterial streets with speed limits above 25 mph||A streamlined request process that places greater emphasis on vulnerable users and the risk of a future crash relative to the traditional method. Results in an updated speed zone order. Authorized by ORS 810.180.
Example: Reduction from 35 to 30 mph, SE 92nd Ave., in 2017
|2. "Traditional"||All streets||Required on arterial streets except on sections eligible for business district statutory speed limits. Uses multiple factors to determine speed limits, including 85th-percentile speeds, crash history, "roadside culture," traffic volumes, and roadway alignment, width and surface. Results in an updated speed zone order. Authorized by ORS 810.180.
Example: Reduction from 40 to 35 mph, SE Stark St., 2017
|3. Statutory||Streets with a speed limit specified by law (see table below)||Requests are relatively simple and fast. Restricted to specific street types and land use areas. Authorized by ORS 811.111.
Example: Reduction from 25 to 20 mph, NE Alberta St., 2017
|4. Special clauses||• Low-traffic neighborhood greenways
• Certain residential streets
|Allows for 5 mph below statutory speed limits on certain streets. Authorized by ORS 810.180.
Example: Reduction from 25 to 20 mph, NE Rodney Ave., 2015
ORS 811.111 describes speed limits deemed appropriate for streets in particular land use areas, such as near a school.
Many streets in Portland have speed limits that are different than statutory speed limits because they have speed zone orders. PBOT must request that a speed zone order be rescinded in order for a statutory speed limit to take effect on an eligible street (request type 3 in the table above).
|Location||Statutory speed (mph)||Details|
|Narrow residential roadway||15||“Located in a residence district and not more than 18 feet wide at any point between two intersections or between an intersection and the end of the roadway”|
|Business district||20||Includes arterial streets. ORS 801.170 defines a business district as "the territory contiguous to a highway when 50 percent or more of the frontage thereon for a distance of 600 feet or more on one side, or 300 feet or more on both sides, is occupied by buildings used for business.”|
|School zone||20||Must meet school zone requirements|
|Residence district||25*||Excludes arterial streets. ORS 801.430 defines a residence district as "territory not comprising a business district that is contiguous to a highway that: (1) Has access to property occupied primarily by multifamily dwellings; or (2) Has an average of 150 feet or less between accesses or approaches to: (a) Dwellings, churches, public parks within cities or other residential service facilities; or (b) Dwellings and buildings used for business."|
|*2017 state legislature granted Portland authority to drop residential speed limits to 20 mph and extended this authority to all Oregon cities in the 2019 session.|
- Visit the Oregon Department of Transportation's online map
- Select "classifications" In the layer catalog on the left
- Select "Federal Functional Class - State" and "Federal Functional Class - Non-State"
- Click "apply"
- Zoom to Portland. Click "legend." Streets that must use the traditional ODOT speed limit request process include all interstates and arterials, except for segments located in business districts.