Inspecting Centre County’s aging collection of almost 500 bridges involves more work each year.

As the bridges slip deeper into disrepair with each passing season, a greater number of them require more frequent inspections, said Karen Michael, assistant executive in charge of design for District 2 of the state Department of Transportation.

With more than 80 structurally deficient and 53 functionally obsolete bridges in the county, inspections are already a year-round job. Looming cuts to infrastructure funding at the federal and state levels will likely add to that workload, Michael said.

“There are always more projects then we have money available,” Michael said. “Our concern is going to continue to be securing a dedicated level of funding. There’s a large need still out there and it remains a question of ‘can we get the funding to continue to do what we need to do?’ ”

The main statistic used for scoring Pennsylvania’s bridges is sufficiency rating, a complex formula that ranks bridges on a 100-point scale, taking into account a bridge’s structural condition, its ability to meet current traffic conditions and how essential it is to the public.

Bridges with sufficiency ratings of 50 to 79 are eligible for federal funds for rehabilitation. Bridges with ratings lower than 50 are eligible for funds for replacement.

“When that rating starts to go under 50, you’re looking at a pretty bad bridge,” said Tom Zilla, transportation planner with the Centre Regional Planning Agency.

According to PennDOT data, 135 state-owned bridges in Centre County have sufficiency ratings between 50 and 79; 28 bridges have ratings lower than 50. Among locally owned bridges, 28 are rated 79 or lower; nine have ratings below 50.

Interactive map of some county bridges

  Finding enough money to keep up with repairs and replacements is an ongoing challenge, said Mike Bloom, senior transportation planner in the county Planning and Community Development Office. At current funding levels, local transportation authorities are already “stretching it kind of thin,” he said.

Bloom said he most fears cuts to federal funding for transportation improvements.

Federal highway funds are distributed to the states according to a formula that takes into account total miles of roads, the rate of vehicles to miles traveled, a state’s population, and the amount of maintenance required due to factors such as weather.

Bridge money is separated from highway funding at the state level — in Pennsylvania’s case, by PennDOT. Money for bridge repair or replacement is doled out based on the total amount of deck area square footage and the total deck area of structurally deficient bridges, according to Bloom.

At the local level, Pennsylvania is divided into metropolitan and rural planning organizations. Oversight for Centre County’s transportation infrastructure is in the hands of the county Metropolitan Planning Organization, composed of local planning and transportation officials, and elected municipal leaders.

Using PennDOT recommendations, the MPO crafts a Transportation Improvement Program — a four-year “to-do” list prioritizing road-related maintenance projects. The TIP, as it’s referred to, is updated every two years.

The county’s current TIP calls for spending $31.5 million, or 47 percent of its $67.5 million budget, on bridge repair and replacement.

“The TIP is constantly in flux,” said Zilla, who’s also an MPO member. “We’re always evaluating the condition of bridges, and our priorities can change. So it’s a moving target.”

All of the bridges on the 2011-2014 TIP are structurally deficient, but not all deficient bridges make it onto the list, due to funding constraints, Zilla said. Nor does a bridge need to be structurally deficient to be placed on the list.

Costs for fixing bridges over the past four years range from $242,543 for the repair of a 21-foot bridge on U.S. Route 322 over state Route 3014 in Boalsburg, to $1.94 million to replace a 42-foot bridge over Penns Creek on state Route 45 in Spring Mills. Zilla estimated the average cost of new bridge deck area is $650 per square foot.

Bridge projects on state-owned roads are funded with federal money and county taxes. The U.S. Department of Transportation covers 80 percent of most projects’ costs.

The responsibility for inspecting locally owned bridges lies with the municipality in which they are located. Those municipalities also are responsible for 20 percent of the cost of any repairs.

“A lot of the structures are in the more rural municipalities, and it’s tough when you’re looking at a relatively small budget to figure out a way to pay for it,” Bloom said. “You’re looking at bridges that can cost from $250,000 to over $1 million. Even at just a 20 percent match, that’s still sizable when looking at a million dollar figure.”

One program that has worked in some cases in Centre County has been “retroactive reimbursement.” Through the Penn- DOT-run Pennsylvania Infrastructure Bank, municipalities can obtain a low-interest loan — one-half of prime rate for up to 10 years — allowing them to complete needed work. To be reimbursed, the municipality must have PennDOT certify the project as structurally adequate, and then petition to add it to the MPO’s TIP.

As the project comes up for funding, which can take years, the municipality receives 80 percent reimbursement from the U.S. DOT. For example, the MPO’s 2011- 2014 TIP includes two retroactive reimbursements, one for $213,333 and another for $259,978.

“It’s an approach our district really likes to use,” Zilla said.

Even so, municipalities struggle to afford much-needed repairs.

Snow Shoe Township is in the midst of trying to figure out a way to pay 20 percent of the $1 million cost of replacing a 103-foot bridge on Kato Road over Beech Creek that has a sufficiency rating of just 20.8.

The bridge sits in the Marcellus Shale fairway, an area that’s seeing increasing truck traffic, Bloom said. It’s also used often by ATVs and users of the Snow Shoe rail-to-trail.

“The township supervisors are trying to get this thing funded, but it’s going to be difficult because of the size of the structure, and at this point, I don’t know if there’s anything they can do as far as rehab on that structure,” Bloom said.

Cliff White can be reached at 235-3928.