By Alexa Nash
Capital News Service
Bridging the gap: Southwest Virginia has the most bridges and culverts in ‘poor’ condition
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 some of the structures they have come to trust are in a troubling state, especially in the southwestern part of the commonwealth.
Of the Virginia Department of Transportation’s nine districts, Bristol has the highest number of bridges and culverts rated D or lower on the agency’s “health index,” an indication of the overall soundness of a structure. (Culverts are tunnels that allow streams or drains to flow under the road.)
Data obtained from VDOT shows that 451 bridges and culverts of over 3,400 in the Bristol district have that low grade, and 182 structures were deemed structurally deficient, or “poor.” The worst structure, a bridge in Scott County, has a grade of 12 on a 100-point scale—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 (said Michelle Earl, communications manager for VDOT’s Bristol district). This is nothing we toy around with.
Many bridges across the state need major repairs and possibly replacement. While the vast, rural Bristol district has more than its share of such bridges, it is aggressively attacking the problem, officials say.
Gary Lester, a bridge engineer for the Bristol district, said 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 they were designed differently than those in Northern Virginia, Fredericksburg, or Hampton Roads—districts that have the fewest structurally deficient bridges. Those 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 VDOT’s 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 the more populous northern and eastern areas of Virginia see most of the funding from VDOT. 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 he focuses on the structurally deficient bridges. This means that the bridge either can be crossed only 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. The district 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).
VDOT plans to announce these new performance measures in the next few weeks.
As the measures take 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.