The Bristol, Va. District has the most bridges and culverts with a grade of “D”or below and are considered in “poor” condition.
By Alexa Nash
It’s difficult to avoid driving over a bridge in Virginia, and motorists often don’t give them a second thought. Drivers are unaware that the structures they have come to trust are in a troubling state, especially in the southwestern part of the Commonwealth.
Out of the Virginia Department of Transportation’s (VDOT) nine districts, Bristol, Va. was found to have the highest amount of bridges and culverts, which are tunnels that allow streams or drains to flow under the road, that are rated as “poor” and have a health index grade of “D.” Data obtained from VDOT shows that 434 bridges and culverts out of over 3400 have that grade, and 184 structures are deemed structurally deficient, or “poor.” The worst structure, a bridge in Scott County, has a grade of about 12 percent, a solid “F.”
Even so, state officials say motorists should not worry.
“Scary terms aside, if there were a problem out there, [the bridges] would be investigated and closed,” Michelle Earl, VDOT Bristol communications manager, said. “This is nothing we toy around with.”
Like many bridges across the state, many need major repair and possibly be replaced. This vast, rural district happens to be solving the problem better than the other eight.
Bristol district Bridge Engineer Gary Lester said that there are many reasons for high number of bridges with low grades, but two stand out: Bristol has more bridges than any other VDOT district, and because of the area’s geography, they are built differently than anywhere else in the state.
The Bristol district is a mountainous region with many streams to cross, and winters are harsh. This means that more salt is used on the roads due to snow, which corrodes the exposed steel in the simply designed bridges.
“In the past, we’ve used a lot of steel beams with timber decks because those were the cheapest and easiest for our crews to put in at the time,” Lester said. Most of the bridges were constructed in the early- to mid- 20th century. The bridges needed to go up fast, so their design was not as calculated as those in Northern Virginia, Fredericksburg or Hampton Roads; districts that have the fewest structurally deficient bridges. These bridges have a design life, or the time in which the bridge is structurally sound, of 50 to 100 years. Bridges built with just steel beams and timber decks in the Bristol district have a design life of about 25 years and need costly rehabilitation much more often.
Dr. David Mokarem, research associate at Virginia Tech, said that the health index is determined by the overall condition of all of the bridge’s parts. He said that traffic, load capacity and the geography of the district are factors in determining the grade.
Age and design life are also important factors. The needs for each district also depends on how much the bridges are used, so it makes sense that northern and eastern Virginia see most of the dollars. That doesn’t mean that Bristol’s situation can be ignored.
“If [the grade] is 65 percent, that’s low,” Mokarem said. “They need to be fixed, repaired … something needs to be done.”
Lester is addressing the need in his district by looking at his bridges differently. He said that he focuses on the structurally deficient bridges. This means that the bridge either can only be crossed by light vehicles and loads, or cannot be used at all until it is rehabilitated or completely reconstructed.
The formula to determining structural deficiency is more accurate than the health index, Lester said. The formula, based on federal guidelines, divides the bridge into its deck structure and substructure and carefully calculates the health of those two parts.
The rating is out of nine. Once a bridge receives a four or below, it is considered structurally deficient and must have signage to advertise its load capability. To put that rating in perspective, a brand-new bridge with a few cracks is given a score of eight.
Every bridge is inspected every two years, and if they are structurally deficient, they are inspected once a year or more, Earl said.
VDOT had a goal over the past five years to decrease the number of structurally deficient bridges in each district by 15 percent. Bristol was the only district to exceed that goal by 27 percent, and is replacing those bridges with ones that have a design life of 100 years.
“We’re looking at the overall load on a bridge before they go structurally deficient, and we’re looking at the condition of the joints to improve those so they don’t leak any water to get down into the structural elements, which will be a new performance measure,” Lester said. These new performance measures are due to be announced by VDOT in the next few weeks.
As these measures take more effect, Lester said that the number of bridges determined to be structurally deficient should go down each year. The district will continue to work hard to bridge the structural and financial gaps.
“There’s new funding available to help improve bridges,” Earl said. “Public safety is our ultimate goal, so if there was an issue out there, it would get closed.”