A `structurally deficient' bridge

Carroll officials close Saw Mill Road span because of problems

August 12, 2007|By Laura McCandlish | Laura McCandlish,Sun Reporter

Only about 70 cars traveled daily on the corroded steel Saw Mill Road bridge over Big Pipe Creek near Union Mills, compared with the approximately 141,000 vehicles that crossed Minnesota's busiest bridge daily until it collapsed into the Mississippi River on Aug. 1.

But like the fallen Interstate 35W bridge in Minneapolis, the Saw Mill Road bridge has been deemed "structurally deficient," meaning the bridge failed in at least one area during the biennial inspections reported to the Federal Highway Administration.

To prevent accidents, county officials said that they closed the Saw Mill Road bridge more than two weeks ago. The county chief of roads operations said the bridge was erected in 1978 but was only meant to last about 10 years. The temporary steel structure will be closed until further notice.

"If the bridge is unsafe, it is closed," county public works director J. Michael Evans said while giving a briefing on the state of the county's bridges.

Fourteen - or 11 percent - of the 132 bridges Carroll County maintains had such structural deficiencies recorded during the last round of inspections in 2005, local officials said.

Three bridges have been repaired or replaced, one is in the design phase, and six are included in the county's community investment program, which earmarked $6.7 million for bridge repairs and replacement in fiscal 2008, said Deborah A. Butler, engineering bureau chief for the county Department of Public Works.

Federal reports show that 8.1 percent of Maryland's approximately 5,000 bridges - and 12.4 percent of bridges nationwide - received a structurally deficient label last year.

Since the eight-lane span in Minneapolis collapsed, officials in Maryland and around the country have spent the past week and a half scrutinizing and reporting on the safety of local bridges.

Carroll County bridges took a hit during Tropical Storm Agnes and Hurricane Eloise during the 1970s, said roads operations chief Benton H. Watson, who has worked for the county since then.

The original Saw Mill Road bridge - and about 60 other Carroll structures - washed away during Tropical Storm Agnes in 1972, Watson said. After being replaced, the Saw Mill bridge was destroyed again during Hurricane Eloise three years later.

Lacking sufficient federal funds to repair the bridges after those storms, some of the county roads remained closed for several years, Watson said. Prefabricated steel panel structures, known as Bailey bridges, were erected as a quicker and less costly fix, he said.

"Those type of structures are a throwback to World War II," Watson said of the temporary bridges.

The most substantial bridges in Carroll cross over the Monocacy River along the western border with Frederick County, he said.

Until the late 1980s, Carroll lacked an agreement with Frederick County to spell out which jurisdiction was responsible for each border bridge, causing many to fall into disrepair, Carroll County Commissioner Julia Walsh Gouge said.

By the early 1990s, Carroll and Frederick negotiated an agreement that each county would be responsible for maintaining half of the bridges that span both borders.

Carroll's bridges that cross into Frederick County include steel bridges at Mummaford and Starners Dam roads, both of which were labeled "functionally obsolete." That designation refers less to safety and more to function, Butler said.

Most of the "functionally obsolete" bridges in the county are one-lane bridges, such as the Saw Mill Road bridge, which should accommodate two-way traffic, she added.

After nearly 30 years of use, the Saw Mill Road bridge has lost sections of its trusses and has rust, gaping holes deteriorated retaining walls and loose and buckling surface panels. There is no sign cautioning that it is a single-lane bridge. And no bridge railings are in place.

Given these deficiencies, engineers inspecting the bridge in 2005 labeled it in "poor condition."

About $650,000 has been budgeted for the reconstruction of the Saw Mill Road bridge, Butler said. But with revived interest in building the regional Union Mills reservoir, county officials said they aren't sure how to proceed.

The Saw Mill Road bridge lies within the planned boundaries for the reservoir and would likely be underwater if that project gains approval, Evans said.

In addition to the "structurally deficient" bridges, 21 percent - or 28 - Carroll County-operated bridges are labeled "functionally obsolete." But Butler said some residents believe that such bridges contribute to the county's rural character.

Many of the deteriorating bridges are in more agricultural areas with lower volumes of cars, she said.

"Most of the deficient bridges are on the back roads," Butler said.

laura.mccandlish@baltsun.com

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