Speed Limits

All 50 states base their speed regulations on the Basic Speed Law. "No person shall drive a vehicle.... at a speed greater than is reasonable or prudent...and in no event at a speed which endangers the safety of persons or property."

The following speed limits are set by state law or Douglas County code:

It is unlawful for the operator of any vehicle to operate at a speed in excess of 25 mph upon any county road in Douglas County unless a different speed is authorized.

  • 25 mph in residential plats and subdivisions.
  • 20 mph in school zones.
  • 50 mph on other roads, unless otherwise established.  

Speed limits between 20 and 50 mph other than those described above are established based on traffic engineering investigations.

The safe and reasonable limit is usually close to the speed at which 85 percent of drivers are traveling. Traffic studies have shown that accidents increase if the speed limit is set far above or below this "85th percentile speed."

Another important measurement, the "pace speed," is the 10 mph range in which the majority of cars are traveling. If the posted limit is lower than the 10 mph pace speed or far above the 85th percentile speed, many drivers will ignore the signs and continue to travel at higher speeds. Other drivers will heed the signs and travel near the posted limit.

When cars travel at different speeds, problems such as tailgating, illegal passing and congestion arise. The gaps in traffic through which vehicles may safely turn or cross the road are also reduced. Studies show that when speeds are not uniform, accidents generally increase. Most drivers travel at speeds that are comfortable for them and are influenced more by traffic and road conditions than the posted speed limit. "Before and after" studies have shown no significant changes in average vehicle speeds after posting new speed limits.

What if I disagree with the posted speed limit?

Call Douglas County Roads and Transportation Services, at (509) 884-7173, your service request and n an investigation based on the principles described here. Please give us as many details as you can about the problems on the road where you are requesting a change. We want to work closely with you to clearly define and address your concerns.

When investigating a traffic problem, we consider not only the vehicle speeds and accident history along the road, but all the road features. These features include the grade, alignment, pavement and shoulder conditions, spacing of intersections, amount and type of traffic, and sight distance (the distance from which the drivers can spot oncoming traffic). Often we can improve driver and pedestrian safety without changing the speed limit.

Posting an appropriate speed limit makes enforcement easier, since most drivers will voluntarily travel at the posted speed. Blatant speeders are spotted easily, safe drivers are not penalized, and patrol officers are‚Äč not asked to enforce arbitrary or unrealistic speed limits.

How are speed limits changed?

If our investigation determines that the speed limit should be changed, the following actions will be taken: The Traffic Division will arrange a public meeting to work toward an agreement on the speed limit.

Public meeting notices will be posted along the road in the area of the proposed speed change and will be sent to local newspapers.

The agreed-upon speed limit will be forwarded to the Board of County Commissioners for consideration and adoption.