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Understanding Neighborhood Speed Limits

November 18, 2019

Speed limits on highways are set by states based on engineering studies, and can be modified based on updated tests. It’s universal that all neighborhood speed limits are much lower than typical city streets. Here’s a look at how these values are determined in western states for highways and neighborhood speed limits.

Safe Neighborhood Driving

Traffic laws are always subject to change based on what happens on city streets. When too many traffic injuries or fatalities occur in a certain neighborhood, it often causes community leaders to demand slower speed limits and the installation of stop signs, additional speed limit signs, or lights and sometimes speed bumps. For stubborn problem areas, Driver Feedback signs can notify and warn speeding drivers more forcefully.

Arizona Speed Limits

Although Arizona’s maximum speed is 75 mph, the state’s default speed limit outside business and residential areas is 65 mph. In business districts the speed limit is 25 mph, whereas the default speed limit near schools is usually 15 mph. At the same time speed limits vary throughout the state, as the maximum speed limit within Phoenix is 55 mph. Streets without lighting in Tucson have reduced speed limits at night. Even if signs are posted, motorists are expected to know the basic speed law.

California Speed Limits

While California’s maximum speed limit is 70 mph, the basic speed law suggests that motorists must drive at a speed that’s “reasonable and prudent” based on road conditions. That means drivers are expected to slow down in cases of fog, darkness, glare or anything else that interferes with traveling at a normal speed. Regardless of speed limits, drivers are not allowed to drive in a manner that endangers the safety of persons or property.

It’s up to drivers to assess the risks involved and to make adjustments for safety no matter what speeds are posted. At the same time the state has a policy of setting speeds that are practical to enforce. In order words, drivers can be cited for unsafe driving even if they are driving below the maximum speed limit. It’s also possible to beat a speeding ticket if you went over the limit but can prove you did so safely.

Washington Speed Limits

The maximum speed limit in Washington state is 75 mph. Most commonly, though, the posted speed limit is 70 mph in rural areas and 60 mph in more urban zones. In school zones the speed limit is 20 mph when children are present. These values may change when new engineering and traffic studies are conducted. Some of the factors engineers look for to determine safe speeds include road conditions, lighting, parking areas, collision rates and activity involving bicyclists and pedestrians.

How Engineering Studies Determine Speed Limits

Engineers try to set speed limits based on the normal flow of traffic, minus the top 15 percentile of fastest drivers. The goal is to set speeds that are reasonable and enforceable. Setting realistic limits is important because drivers are more likely to comply with the law if they agree with reasonable speeds. Too many unreasonable regulations can lead to lack of conformity with the law. Engineers also take into account factors such as congestion, lane widths and surface conditions.


Every state has its own traffic speed limit standards, dependent on the needs of their community. In residential areas drivers know they must slow down, but it helps to remind them with signs. Contact Zumar at our Arizona, California or Washington location to learn more about neighborhood speed limits and proper signage.

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