Speed limits/USA View history

Revision as of 15:50, 21 February 2016 by PesachZ (talk | contribs) (Segment cut 200 ft rationale)

Speed limit (SL) data added to segments in the WME is used in the Waze client app to display a Wazer's speed relative to the speed limit. In addition, the app alerts Wazers if they exceed the speed limit designated on the Waze map.

This article discusses When, How, and Which speed limits should be added to the map in the USA. The guidelines set forth below may be expanded by local regional or state guidance, Please be sure to check your local wiki for any relevant information as well.

Speed Limit Sign


Which speed limits should be added to the map

The ONLY speed limits added to the map are Regulatory Speed Limits. These must match federal, state, and municipal laws or regulations that designate enforceable maximum speeds for passenger vehicles. These are marked with black lettering on white rectangular signs.


Fixed regulatory speed limits

Any fixed (non-variable) speed limits posted on the regulatory black and white signs should be added to the road corresponding segments in the WME.


Ramps

If there is a regulatory speed limit sign posted on the ramp itself, this speed limit should be added for the ramp segments.

If the speed limit for the segments on either end of the ramp are the same, then that limit should be added to the ramp as well.

Ramps with only advisory speed limit signs, as shown below, should have no speed limit in the WME.


At grade connectors

AGCs follow these 3 basic rules in this order of preference (apply first match):

  1. If it has its own dedicated posted regulation SL, use it.
  2. If the SL before and after are the same, use it
  3. If it physically looks and functions as a ramp, leave it blank, otherwise use the SL of the segment feeding into the AGC (s-in)

Click Expand for details on the rationale behind these rules.

Basically there are three types of AGCs

  1. Extra segments we add to the map for ETA or prompt control, which are essentially just us mapping a specific lane of the road. These AGCs typically terminate at the intersection, and can be considered a part of the road they are on.
    These would share the same SL as the segment they are coming from/run parallel with.(s-in)
  2. Segments that functionally are ramps which for some reason are not using the ramp type, these are median separated from the regular road, and includes acceleration / deceleration type lanes.
    We can treat these just as ramps.
  3. Actual strips of road physically connecting different streets. Like triangle intersections these may or may not be named streets. With these in general they would legally follow the SL of the segment leading into them since the SL is applied until you enter a new zone which supercedes them. Therefore until you traverse the AGC to the new road where a new SL is in place you are still bound by the previous SL.

Private

Speed limits that are designated on private property using regulatory signs may be added to road segments on the Waze map at the discretion of the Regional Coordinator or State Managers. Be sure to check your local wiki for guidance.

Speed Limits are added to parking lot and private road types by changing type to street, adding limits, then reverting to the original road type.

Work zones

Work Zone Speed Limit sign
Work Zone Speed Limit sign

Speed limits in work zones are often lowered to protect workers and prevent collisions. If these speed limits appear on regulatory black and white signs, they MAY be added to the associated WME road segments, IF supported by your local area. However, this should be done in consultation with State Managers or Regional Coordinators, so that the temporary speed limits can be monitored for changes. It may be prudent to only modify the speed limit for long-term construction projects, each region must decide what terms are best locally.

Another option is to add the underlying to speed limit to the map for now, and put the work zone speed limit in a specially marked UR note (or otherwise keep track of it). Being that as of the writing of this page the speed limit feature is not yet functional in the production client app, this will prevent redundant effort to go back and fix the speed limits if the construction ends before the speed limit feature is rolled out.

Check your regional or state wiki to see which work zone limits should be added in your area, and the process for monitoring them.
Click [show] below for links to your wiki.


Variable Speed Limits

Variable Speed Limits

The WME and Waze app do not support Variable Speed Limits (VSLs) that are changed based on traffic and road conditions. These VSLs can be changed at any time by government officials. If there is a 'standard' speed limit at which the signs on a stretch of road are set for the majority of the time, this 'standard' speed COULD BE added to the associated road segments in the WME. However, the setting of any speed limit on a road with VSLs must be made in consultation with the appropriate State Manager, or Regional Coordinator.


Time based speed limits

As of February 2016, the WME and Waze App only support a single speed limit, without variation for time of day, or day of the week. 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).

For example let's assume a 35mph street has a reduced speed limit of 20mph for the hours of 7am-4pm School Days. Then it is not in effect every single day, and even the days it is in effect, it's only for 9 hours. The rest of the time the 35mph limit is in effect. This segment should be set to the 35mph limit.


Unsupported speed limits

The following speed limits are unsupported by the WME and the Waze app, and MUST NOT be added to road segments in the WME. Road segments with posted 'advisory' speeds or special speed limits should continue the Speed Limit for passenger vehicles as posted on the black and white signs pictured above.

Advisory speed limits

In addition, yellow 'advisory' speed signs (as shown below) are usually not enforceable; therefore, 'advisory' speeds, like the ones shown below, should NOT be added to the waze map.

Special speed limits

As of February 2016, the WME and Waze App only support maximum speed limits for passenger vehicles, without variation for time of day, or day of the week. Specialty, also known as 'bannered' speed limits, like the ones shown below, should NOT be added to the Waze map.

School zone speed limits that are in effect 24 hrs per day, and 365 days a year, should be added to the map.


Where speed limits change

Speed limits should change where they legally go in effect for your state, that may be at the sign, a specified distance before the sign, or the nearest intersection; check your local wiki for the practice in your area. 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.
  • Depending on your local guidance this distance may be expanded above 200 feet, always confirm local practice.
  • A new junction should always be added if it will be more than 1,000 feet from the nearest existing, or potential junction.


Creating a new junction for a speed limit change

When creating a new junction solely for the sake of showing a speed limit change, you can attempt to get more value from the junction. Survey the area around the speed limit change, determine if there is a PLR or other segment which should be connected to the road and would result in a junction. You may find that there's a parking lot which could benefit from being added to the map within the allowable distance of 200 feet (or more depending on your area) to where the SL changes. In such a case connect that segment and use that junction. Otherwise you should create a new junction to show where the SL changes.

Click Expand for details on the rationale behind these rules.

I choose 200 feet because less than that the difference is negligible, and not much different than delay we expect with GPS lag and error anyway. Think of where you hear the turn prompts sometimes up to 200' before you reach the intersection. I already said that adding a note does not have a penalty and that was not at all part of my ration now for the 200 foot buffer. The reason to give a minimum of 200 feet from the nearest junction as a father is to account for turns LA calculations if we create junction nodes very close to intersections we will effectively eliminate with his ability to tell the difference in time it takes to go straight VS turn left or right. And unless you want to start adding junction boxes to each of these situations compensate for that which is a lot more work a lot more strain on the servers and going to make it harder to manage him that since they lock all the segments we have to come up with a compromise that is still visibly accurate without anything noticeably different to the user yet maintaining the ability for ways to calculate proper time through intersections I think less than 200 feet poses a significant risk the ETA calculations, if it was slightly more than 200 feet to the next junction maybe 250 I could still see that need you not married cifically to the number 200. So we have to put some number out there otherwise every editor will interpreted differently I won't say that anything that's more than 5 meters away is far enough away to get a new junction