Washington follows the national guidelines for adding speed limits to the map. There are a few items left up to local guidance which will be enumerated below.
Washington law
Washington law includes the following restrictions on the designation of speed limits. [1]
Maximum speed limits are as follows, unless otherwise signed/posted:
25 miles an hour on all city/town roads;
50 miles an hour on county roads;
60 miles an hour on state highways.
Speed limits may be revised by local authority after a traffic study and then posted.
Maximum speed limits for local jurisdictions are:
30 miles an hour on arterial streets within the City of Seattle. [2]
National guidance recap
The ONLY speed limits which should be added to the map are Regulatory Speed Limits. These are marked with black lettering on white rectangular signs.
'Advisory' or speciality speed limits that are unsupported by the WME and the Waze app, and MUST NOT be added to road segments in the WME, including:
Advisory speeds
Truck speed limits
Night speed limits
Segments with time based different speed limits should use the speed limit which is in effect the majority of the time (most hours of the day, days of the week).
Speed limits should change where they legally go in effect. When a speed limit changes in the middle of a segment, a new junction should added to support the SL change. However a new junction should never be added for a SL if it will be within 200 feet of an existing junction, or potential junction.
Work zone speed limits
A work zone (WZ) may have a lower advisory speed limit (SL) posted in black on orange
, or a regulatory speed limit posted in black on white with an orange "Work Zone" banner across the top .
We only consider the regulatory signs, and never map advisory speed limits.
Interim guidance in Washington until the Speed Limit feature goes live to production to production in the client app.
Only add Work Zone SLs if they are anticipated to persist more than a year.
For projects expected to last less than a year:
Add the regular underlying SL to the segments
Document the WZ SL as a [NOTE] UR with the keyword mph included in the text.
After the Speed Limit feature goes live in the production client app adding WZ SLs to segments will generally be allowed.
Typically only projects which are expected to last at least 3 months should be added to the map.
The underlying SL, and expected project completion date should be documented in a [CONSTRUCTION] UR with the keyword mph included in the text.
Projects of shorter duration may be added as well, IF the editor has access to frequent status updates on the project, and is willing to monitor and adjust as soon as the SL is restored.
Where speed limits change
The Washington supplement to the MUTCD stipulates that: A Speed Limit sign in a speed zone shall be located at or just beyond the point where the zone begins. If the zone begins at an intersection, the first Speed Limit sign for that zone shall be the Speed Limit sign normally erected beyond the intersection conforming to the standard sequence of signs at intersections.[3]
Washington is a state where the speed limits are absolute and are enforceable from statute; speed limits need-not be posted to be enforced.
When adding speed limits to WME we should try to be as accurate as reasonable, while still preserving data for turn delays. Therefore if a speed limit changes in middle of a segment we will create a new junction to support the SL change. However if there is already an existing junction, or we can see the need to create a new junction to connect another segment to the road within 200 feet of the speed limit sign, we should mark the SL change using that existing (potential) junction node.
If at the editor's discretion in consultation with local managers, it is determined that a new junction to support a SL change between 200 - 1,000 feet away from a junction would have a negative impact on turn delay calculations, they may instead affect the SL change at an existing (potential) junction up to 1,000 feet away from the SL sign. This may be because the SL change is posted in middle of turning or exit lane where traffic regularly backs up from the following junction to before the position of the SL sign.
, or a regulatory speed limit posted in black on white with an orange "Work Zone" banner across the top