Road Wizard 2/21/2020

Topics: Guardrail Criteria, Road Debris Clean Up


Dear Road Wizard:  What are the criteria for a road to have a guard rail installed?  Christine

Most local agencies, and even some state agencies, do not have definitive criteria for guardrail installation practices.

Sorry to get a little technical, but I had to quote the AASHTO Roadside Design Guide instead of the usual wizard sources. It states the following: “The primary purpose of all roadside barriers is to reduce the probability of an errant vehicle striking a fixed object or terrain feature off the traveled way that is less forgiving than striking the barrier itself.”

The design guide presents current information and operating practices related to roadway safety and is considered one of the definitive guides on roadside protection. Numerous factors are considered when determining the need for a guard rail, such as:  design speed, traffic volume, installation costs, maintenance costs (once installed), and crash costs (probability of crash types and their severity), amongst many others that can become very technical--even for this wizard!

Dear Road Wizard:  Who cleans up all the random road debris? Hank

For “natural” occurring debris like rocks, tree limbs, and some, ACHD crews usually address and remove these items. I answered previous questions about street sweeping and leaves on January 3rd of this year and November 1st of last year.

Crash debris is collected by tow companies that are assisting inoperable vehicles. When dangerous substances are involved, ACHD will work with a hazardous material clean-up crew if needed.

There are also instances when debris is a safety hazard, and in those cases ACHD crews may also assist in clean-up efforts.


Do you have a question for the Road Wizard? You can send them to: