On a recent sunny morning, swallows dart above the Clark Fork River alongside the rusty steel girders that crisscross the Madison Street bridge's underbelly. Looking up from beneath the span on the pedestrian walkway where two women jog, one sees that the 55-year-old Madison, with cement eroding along its edges, is showing its age.
"Those are items that we know about," says Montana Department of Transportation Bridge Bureau Chief Kent Barnes. "We need to address them."
Missoula County has 159 public bridges that transport buses, trucks and cars across rivers, irrigation ditches and railroad tracks. The Madison is one of 7 bridges deemed by state and federal engineers as being structurally deficient. That classification can be triggered by benign defects, such as rough roadways and narrow lanes, or they can be more serious problems, in this case with deficiencies in the bridge's superstructure, the area between concrete footings and the span's surface above.
Barnes notes that regular MDOT safety inspections show that the Madison Street Bridge is safe, despite being rated at 35.5 on a federal database that runs from zero, meaning entirely insufficient, to 100, when gauging a bridge's ability to stay in service.
Like the Madison, the span across Higgins, constructed in 1962, is also considered structurally deficient, in part because its superstructure is in poor condition.
The 56-year-old Russell Street Bridge, meanwhile, is slated to be replaced beginning in 2016 as part of the Russell Street redesign. It's also classified as structurally deficient.
Missoula's aging bridges aren't unusual, nor are the mounting costs that will be required to maintain and replace them. According to the nonprofit Transportation for America, which advocates for healthy roadways, the average American bridge is 42 years old. Roughly 11 percent of the nation's 678,000 highway bridges are considered structurally deficient.
Last month's bridge collapse along Interstate 5 above the Skagit River in Washington State has revived a national discussion about bridge safety and how to pay for maintaining and replacing the country's aging infrastructure. On May 23, a portion of the Skagit bridge near Mount Vernon, 60 miles north of Seattle, collapsed when a truck carrying drilling equipment hit an overhead girder and sent a segment of the span and three vehicles tumbling into the water below.
National Transportation Safety Board Chair Debbie Hersman called the accident a wake-up call. "At the end of the day," she said, "it's about preventing an accident like this."
The I-5 incident marked the second bridge failure since 2007, when Interstate Highway 35 over the Mississippi River near Minneapolis collapsed and killed 13 people.
The Skagit was constructed in 1955. Marking a design trait of its era, the span lacked duplicative elements capable of acting as a backup if one element failed, a vulnerability shared with the bridge in Minnesota and with 15 Missoula County bridges under state and local purview, including the Higgins Avenue, Madison and Russell street bridges.
The term used for such structures is "fracture critical." "What fracture critical means to us is that we pay more attention to it," Barnes says. "They get closer scrutiny."
The federal Highway Trust Fund pays for the lion's share of bridge repairs and replacements nationally. But as fewer miles are driven and vehicles become more gas efficient, less fuel tax money flows into federal coffers. The Congressional Budget Office projects that the Highway Trust Fund will run a $14 billion deficit by 2015.
Federal budget crunchers estimate that roughly $20 billion annually will be required during the next 15 years to rehabilitate bridges across the country. That's a little more than twice what local, state and federal governments are spending now.
Despite those numbers, Congress hasn't raised the country's 18.4-cent-per-gallon gas tax since 1993.
Faced with flat funding, states are individually raising fuel taxes to help pay for infrastructure repairs. Last month, Maryland increased its tax for the first time in 20 years, upping it from 23.5 cents to 27.5, with another 8-cent increase slated for 2016. Wyoming also passed a 10-cent increase this year and in a post-Skagit collapse Washington state, lawmakers have renewed calls to raise that state's 37-cent-per-gallon fuel tax.
Montana's gas tax has remained at 27 cents per gallon for nearly 20 years. During the 2013 session, Missoula Democratic Rep. Nancy Wilson proposed a 1-cent-per-gallon increase. The bill died in committee. According to the MDT, available federal bridge funding climbed until 2012, but is falling flat through 2014, with roughly $37 million dedicated to bridge funding this year.
In the coming months, Congress begins hashing out reauthorization of transportation funding bills that are slated to expire next year. Barnes notes that the state's infrastructure needs aren't going to go away.
"We either have to cut our spending or increase our revenue stream," he says.
In Missoula, MDT is launching a feasibility study to weigh future plans for the Higgins Avenue and Madison Street bridges. By 2014, agency engineers hope to have a draft plan ready that spells out the best way to maintain and improve the bridges in light of funding constraints.