Guardrails

Motorists pass along Veteran's Memorial Parkway in Anniston near the Iron Mountain Road intersection. The section of road has no guardrails. (Photo by Trent Penny/The Anniston Star)

Tuesday evening a woman’s SUV careened off Veterans Memorial Parkway when she swerved to avoid a deer, she said, and in the wake of that crash some residents are asking: Why wasn’t there a guardrail on the road? 

The northbound side of the four-lane highway, about a mile from the intersection of U.S. 431 and Alabama 21, is bordered by a deep embankment, steep enough that an Alabama State Troopers helicopter hovered beside it, with propeller blades parallel to the roadway, to search the wreck site Wednesday morning. The SUV’s driver, Ashley Johnson, spent about 17 hours down that embankment, during which she crawled back to her vehicle after being thrown from it during the crash. 

Similarly steep drop-offs line the parkway, which traverses the mountainous territory that once was part of Fort McClellan. Drivers zip past several spots where treetops are separated from the pavement only by empty space.

That stretch of highway is under the purview of the Alabama Department of Transportation. According to Tony Harris, ALDOT media and communications bureau chief, guardrail planning is part of the road design process. 

“There is design criteria we could apply that looks at when a guardrail is warranted in an area or not,” Harris said. “But you can never use enough guardrail to overcome driver error or driver behavior. We can’t engineer around those things.” 

Harris said the organization is receptive to requests for more guardrails from the community. Those requests can be made through relevant local governing bodies, like a mayor or the county commission. 

But what kind of expectations should local drivers have when it comes to guardrails?

“A better word than guardrail might be ‘guiderail,’ though I say that sort of tongue-in-cheek,” said Brian Rosenbalm, Calhoun County engineer. “The purpose of a straight rail is to guide a vehicle back onto the travelway and protect it from going on the other side.”

Posts at the end of the rail are called end anchors, designed to take a direct hit from an oncoming vehicle, Rosenbalm said. They’re designed to crumple and distribute the force of an impact to make it dissipate from the vehicle, crumpling the rail section as the vehicle slows. The metal railing in between those end points, according to a Federal Highway Administration explainer, can redirect, stop or slow a vehicle on impact, depending on the angle from which it hits. 

Highway Administration data shows that roadway departure crashes — those in which a vehicle leaves the roadway — accounted for 52 percent of fatal crashes in the United States in 2017, the most recently published year. A total of 19,233 people died from roadway departures that year, of a total 37,133 crash deaths. 

That same year, there were 864 fatal crashes in Alabama, according to the National Highway Traffic Safety Administration. Of those, 343 were “fixed-object” crashes, in which a vehicle left the roadway to strike a generally immobile object, like a power pole, tree or other structure. 

A Purdue University study published in 2014 compared 2,124 single-vehicle road accidents between 2008 and 2012 on more than 500 roads paired for their similarities, excluding safety features like guardrails, concrete and cable barriers. 

According to the study, guardrails reduced the risk of injury by 65 percent; cable barriers reduced risk by 85 percent. 

A spokesperson from the Federal Highway Administration’s office of public affairs, speaking on behalf of the organization, wrote in an email Thursday that guardrails are often the “last line of defense for drivers and their passengers.”

“A guardrail cannot prevent injury or save the lives of drivers and their passengers in every situation,” the statement read, and noted that many factors affect guardrail performance, including the size and speed of a vehicle that hits the rail. 

Rosenbalm said the county typically looks at installing guardrails both during the road design process and whenever roads are resurfaced. There are certain criteria to use when designing a road to determine whether to include a guardrail, called warrant criteria, he said, which helps determine whether a site warrants a particular safety feature, like guardrails or traffic lights. 

For barriers like guardrails, considerations include the expected speeds travelers will drive on a road, the steepness of embankments beside the road, curves and other criteria. 

“If there was a cliff 300 feet away, if I ran off the road I would have plenty of time to correct myself,” Rosenbalm said. “What if that same cliff was 3 feet off the pavement? You’d go, ‘Yeah, I need it.’”

Assistant Metro Editor Ben Nunnally: 256-235-3560. 

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