Summary and Key Take-Aways for Speed Limit Setting on Locally-Controlled Roads
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The first step in the process is to determine whether the road is considered a “local road” as classified using the California Road Systems Map. If it is, then no E&TS is required and local staff may set the speed limit as they deem appropriate (in 5 mph increments starting at 15 mph), including using prima facie speed limits if desired.
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If the road is not a local road, the next step is to determine whether the road would have a prima facie speed limit. Roadways with prima facie speed limits include business activity districts, business districts, residential districts, senior zones, school zones, playground zones, alleys, and railroad crossings or uncontrolled intersections with obstructed views.
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Business activity districts may be set to 20 or 25 mph, residential, business and senior zones may be set to 25 mph, school zones may be set to 25 or 15 mph, playground zones may be set to 25 mph, and alleys and railroad crossings or uncontrolled intersections with obstructed views may be set to 15 mph.
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Some prima facie zones do require an E&TS and others do not. Some prima facie zones require posting of speed limit signs and others do not.
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Refer to CVC § 22352, § 22358.9, § 22358.4, and § 22357.1 for definitions of these zones and details on requirements for different speed limits.
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If the road is not local and is not a prima facie zone, an E&TS must be performed, and the starting point for speed limit setting will be the nearest 5 mph increment from the measured 85th percentile speed.
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Rounding up or rounding down:
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If the nearest 5 mph increment is down (e.g., 32.4 mph rounds to 30 mph), then practitioners should round down and move on to consider whether there are any roadside conditions not apparent to the driver (see CVC § 627 and CVC § 22358.6 (b)-(c)) that might lead to another 5 mph reduction.
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If the nearest 5 mph increment is up (e.g., 32.5 mph rounds to 35 mph), then practitioners can choose to round up. If they do so, they may move on to consider whether there are any roadside conditions not apparent to the driver (see CVC § 627 and CVC § 22358.6 (b)-(c)) that might lead to another 5 mph reduction.
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If the nearest 5 mph increment is up (e.g., 32.5 mph rounds to 35 mph), then practitioners can choose instead to round down. If they do so, they cannot take another 5 mph reduction for roadside conditions not apparent to the driver.
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After rounding and accounting for roadside conditions not apparent to the driver (if permissible), practitioners can consider whether the roadway meets the definition of either a Safety Corridor or a Land or Facility that Generates High Concentrations of Bicyclists or Pedestrians. If yes, then the speed limit can be reduced another 5 mph (note: if the roadway meets both definitions, the reduction can be taken only once). See CVC § 22358.7 for further details.
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Finally, once all of the above has been considered, if local practitioners find that the speed limit dictated by the E&TS and associated reductions is still more than is reasonable or safe, the currently posted speed limit can be retained or the immediately prior posted speed limit can be restored. These actions can only be taken if no general purpose lanes have been added and, if the immediately prior speed limit is elected, the reduction from the currently posted speed limit can be no greater than 5 mph. See CVC § 22358.8 for more details.
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NOTE: regardless of which reductions are taken for which reasons, in cases where an E&TS is required, the speed limit may not be set more than 12.4 mph below the measured 85th percentile speed.
2. Questions for Local Jurisdictions to Consider
As local jurisdictions conduct a new citywide E&TS and/or explore lowering speed limits on roadways, some general questions to consider include:
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Does your jurisdiction have a Vision Zero Action Plan?
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Has your jurisdiction identified a High Injury Network (HIN)?
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Has your city completed a Local Road Safety Plan (LRSP)?
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Does your city have any other documents/plans with an analysis of roadways recommended for speed reductions?
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Are there any pending City Council or City Manager requests to review speed limits at specific sites?
If a local jurisdiction answers yes to any of the above questions, they may already have a preliminary list of roads to consider for speed reduction.
For some local jurisdictions, it may make more sense to use a segment-specific approach to reduce speed limits. Some questions to consider include:
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For each segment in your E&TS, is the posted speed limit prioritizing vehicle throughput and higher speeds than it needs to be for safety?
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Are there any longer corridors in your current E&TS that have differing prevailing speeds (due to changes in road geometry or land use changes) and should be divided into multiple segments?
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Did your jurisdiction raise any speed limits from 2009 to 2018?
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Do any corridors qualify as a Business Activity District?
If a local jurisdiction answers yes to any of the above questions, they may already have a preliminary list of road segments to consider for speed reduction.
As roads or road segments qualify for speed reductions by road classification or prima facie designation and no longer require an E&TS, it may be prudent to document this change in your latest E&TS with a justification to improve enforceability of the new speed limit.
Another consideration is if there is political will to reduce speeds. Agencies may face insurmountable challenges if their plans do not align with the current politics in their community. Specifically, is reducing speed limits consistent with your jurisdiction’s stated goals and plans or aligned with the perspectives of your current City Council?
3. Collect Supporting Materials to Enact Reduced Speed Zones
Once a local jurisdiction has made the decision to implement reduced speed zones, the next step is to gather supporting materials to help with identifying sites and to ensure that the new speed zone is enforceable. Please see below for a list of materials to collect and review.
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Current citywide E&TS. The provisions of AB 43 and AB 1938 allow local jurisdictions to apply additional speed reductions from the 85th percentile based on certain criteria.
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Immediately prior citywide E&TS (typically from 2009 and 2018). Local jurisdictions may elect to retain/restore these speed limits if the current E&TS indicates a higher 85th percentile speed.
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California Road System Functional Classification (maintained by Caltrans). Specific considerations for speed limit reduction vary by road type.
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Local capital improvement plans and/or funded safety improvements (e.g., Highway Safety Improvement Program (HSIP), Safe Routes to School (SRTS), Active Transportation Program (ATP), Federal Safe Streets and Roads for All (SS4A), county-based funds, etc.). Consider implementing speed limit reductions in conjunction with other traffic safety improvements to maximize benefits through integration of safe speeds and safe road design
- Map of fatal and serious injury crashes in the jurisdiction. This data-driven approach would reduce speed limits on the roads contributing to the highest number of fatalities and serious injuries, and may have the greatest impact on saving lives. Potential sources for this data include the local Vision Zero plan and/or High Injury Network map, Local Road Safety Plan (LRSP), Systemic Safety Analysis Report Program (SSARP), or the Transportation Injury Mapping System (TIMS). If using TIMS, select the “SWITRS GIS Map” tool and examine crash severity using the “Crash Severity” variable under the Crash filters category (see more detail here).
