The Pittsburgh Press from Pittsburgh, Pennsylvania • Page 318

Anatomy Of A Bridge LD BRIDGES are like old men who have neglected their health. Salt, water and weather do to steel and concrete what abuse and unconcern do to human tissue. Age alone makes bones fragile and muscles weak. On a bridge, age makes steel brittle and limits its ability to bear heavy loads. Rust, like arthritis, impairs joints.

Wigs can hide a bald spot or dye can eliminate gray hair, but they don't change a man's age. A thin layer of asphalt can hide potholes, or paint can mask metal corrosion, but they don't enable a bridge to last forever. But this is not a health story. This is an anatomy of a bridge the 10th Street Bridge, a suspension span built in 1931-32 and carrying more than By Joe Grata MAN (SIDEWALK EXPANSION DAM PLATE CLEAR OF TOWER CLOSURE (PLATE AT (FIRST SECTION OF EXPANSION DAM COVER PLATE MISSING BRIDGE RDWY. 22-0 (LENGTH OF TRACKS BRIDGE.

FULL 8 TYP. 22-0 44'0 FORM PLATES UNDER TROLLEY TRACKS HAVE ALMOST COMPLETELY el CORRODED AWAY IN THESE AREAS. NOTE FOR SECTION SHEET EXPANSION DAM HEAVILY CORRODED DUE TO WATER LEAKAGE SIDEWALK EXPANSION CAM PLATE IS 12 CLEAR OF TONER CLOSURE PLATE AT 11-PANELS 25'-0" 29-PANELS 25'-0" I 11-PANELS 25'-0" 275-0 725 -0 275'-0" -TO CARSON ST. (SIDEWALK ON BOTH SIDES OF 4 LANE ROADWAY) TO 2ND. 2.5% 2.5% POOL EL.

710.0 SOUTH BRANCH NN3d 8 PIER PIER NN3d 088 HIJON ABUT. CENTRAL 8 L.E.R.R. NO. SOUTH TENTH OVER STREET BRIDGE NO. LINCOLN R.R, ABUT.

PARKWAY MONONGAHELA RIVER- PITTSBURGH, PA. ELEV. LOOKING WEST (DOWNSTREAM) OVERALL LENGTH OF BRIDGE 1275 FT. PLATE- I BRIDGE BUILT 1931-32 000 vehicles a day across the Monongahela River between Second Avenue at the Armstrong Tunnels and Carson Street on the South Side. From a distance, the bridge appears to be in substantial physical condition.

In fact, the symmetry of the cables, the two huge steel towers on which they're draped and the graceful curves form an impressive picture of the city's architecturally unique structure. Then after reading a $112,000 in-depth engineering report, and learning $1.5 million in repairs are needed now, you wonder whether you'll ever chance walking or driving across the 10th Street Bridge again. In fact, Salvucci Associates the consultants hired to do the inspection, found so much wrong, the county was forced to make $50,000 in temporary repairs under an emergency contract in the summer of 1975. Plus, the consultants detected three leaks in the two 24-inch-diameter water mains and three leaks in a 16-inch-diameter natural gas main parts of the utility "lifelines" carried underneath sidewalks and the bridge deck. Other than minor work on the four-lane deck and some repainting, the 10th Street Bridge like so many of the 1,699 other bridges in Allegheny County essentially has been neglected.

In 1935, 1937 and 1975, bridge maintenance crews pumped water out of the 84-million-pound concrete vaults which anchor the 13-inch-thick bundles of main cables, although the vaults at both shore abutments continue to leak today. In 1941, wrought-iron plates were installed. In 1952 and 1966, river navigation lights were replaced, and also in 1966, the bridge lighting system was rehabilitated. Fortunately, the 10th Street Bridge was "over-designed" to carry weights far in excess of normal traffic because heavy trolleys once shuttled across the span. Therefore, following emergency repairs during which the weight limit was lowered to 15 tons two summers ago, the bridge was reopened to unrestricted legal loads the status today.

"If further deterioration does occur," warned the consultant, "it will require only a short period of time until the bridge would have to be either limited in load or closed." The bridge superstructure was assessed to be in "excellent condition," and if appropriate repairs are made now, and if reasonable maintenance continues in the future, Salvucci estimated the span could be in service for another 50 years. The county expects to meet the challenge -HOLE IN SIDE OF HATCHINAY ROADINAY SIDE. BOTTOM INSIDE HORIZONTAL LEG OF FASCIA GONE. F.S. -rL.

NORTH ANCHORAGE of those "ifs" and somehow came up with $1.5 million to let the contract for the rehabilitation work later this year. "It's absolutely essential not only to save what we've got but also because 10th Street Bridge will be a critical artery in the near future," according to John B. Drake, county bridge engineer. "'The bridge will have to bear the overload when the state restricts travel on the Fort Pitt and Liberty bridges for major overhauls in coming years." Exactly what ails the 10th Street Bridge? Here's a partial diagnosis of some of the pressing problems: Most drain troughs and downspouts have been removed no one knows when or by THE PITTSBURGH PRESS ROTO, JUNE 5, 1977.