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Where and When to Install Yellow Speed Limit Signs

May 17, 2018

The placement of yellow speed limit signs is important to keep traffic under control. While black and white signs indicate the official speed limit of an area, yellow speed limit signs serve a more cautionary purpose. Some signs might give additional instruction such as “slow down.” Here are details about where to place yellow speed limit signs for maximum effect.

Standard Regulations

The Federal Highway Administration (FHWA) has established standards for how regulatory signs are posted. Regulatory signs, including speed limit signs, must be posted at or near where they apply. The requirements on the sign must be clear and visible and be illuminated so that it appears the same way day or night. The values of speed limits, as defined by the FHWA, must be multiples of 10 km/h or 5 mph. No sign should display over three speed limits.

Yellow speed limit signs are often additions to other yellow cautionary signs, such as on sharp curves. The speed limit on a yellow sign is more of a suggestion than a requirement, while black or white signs display the actual speed limit determined by officials. These signs usually need to be replaced once every five years due to wear and tear from environmental factors.

Here are some of the factors in which local agencies and states work together on in determining specific speed limits:

  • pace speed
  • road and shoulder characteristics and condition
  • grade, alignment and sight distance
  • parking availability, roadside development and pedestrian activity
  • accident history

Alternatives to Speed Limit Signs

You’ll find yellow speed limit signs on freeways, expressways and conventional roads. While these signs are necessary to remind drivers not to drive as fast as possible, there are situations where alternatives to speed limit signs are more appropriate. A yield sign might be more effective around curves to warn drivers to slow down due to an upcoming stop. In some cases a “yield ahead” sign is needed in addition to a yield sign if visibility is an issue.

“Reduce Speed” is another familiar sign that is commanding drivers to slow down rather than just inform them of the suggested or official speed limit. These signs are placed near the end of freeways or where a busy expressway leads into a more residential area.

Double Signs

Speed limit signs for trucks are often separate from regular passenger cars. Truck speeds are directed at big rigs that are expected to stay in slower lanes. The signs are usually posted together so that drivers in smaller cars are aware of how fast they can go to pass up big trucks.

Another scenario in which you may see two speed limit signs is on a road in which the speed limit changes at night. Typically the daytime speed limit sign is white with black letters whereas the nighttime speed limit sign in the inverse.

Contact us at Zumar to work with experienced professionals who can answer your questions and offer a Free Quote on what type of signs are appropriate for your area.

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