Repair Work to Begin on Route 372 Norman Wood Bridge
– Depending on weather, work may take a month to complete –
Harrisburg – Work begins today to repair the Route 372 Norman Wood Bridge over the Susquehanna River between Lancaster and York counties. The bridge has been closed to all traffic since Monday afternoon, Sept. 28, after bridge inspection crews discovered a large vertical crack measuring approximately eight feet long in a steel girder on the south side of the bridge. The Norman Wood Bridge is a two-lane, 21-span bridge that was built in 1968 and carries on average a little more than 4,300 vehicles a day.
The Pennsylvania Department of Transportation has directed J.D. Eckman, Inc. – a private construction company headquartered in Atglen, Pennsylvania and on contract with PennDOT – to make the repair to the girder by essentially bolting two steel plates over the crack. The steel plates, measuring approximately 5 feet by 14 feet, will be bolted one on top of the other on the south side of the girder to restore structural integrity to the girder and the bridge.
“Once mobilized and the materials for the repair have been procured and delivered on-site, the contractor intends to work during the daylight hours seven days a week” said Mike Keiser, district executive for PennDOT Engineering District 8 which covers south central Pennsylvania. “For safety reasons, considering the height and location of the bridge, work will not be conducted during the overnight hours. We expect that it will take about a month – hopefully sooner — to complete the repair. Though the cost estimate is preliminary and very general at this time, it will likely amount to several hundred thousand dollars.”
The initial work involves the contractor starting to mobilize today and this weekend. The contractor on Monday will begin setting up its rigging and equipment on the bridge so that their crews can safely conduct their work. One of the early operations will be drilling holes into the steel girder in order to stop the further spread of existing cracks. This is a standard construction technique in dealing with cracks in steel bridge beams and girders. The weight of the bridge on the girder (called the dead load) will need to be lifted off of the girder by a detailed jacking system. This is a complicated procedure. The south side of the girder will then need to be prepared for the steel plates, which involves removing three vertical stiffeners (i.e., the steel supports situated perpendicular to the web of the girder that flank the crack). The steel plates — that will be fabricated by High Steel, Inc. in Lancaster, Pa. – will span the crack and be bolted onto the south side of the girder. The vertical stiffeners will then be rebuilt onto the girder.
“It is possible that we may be able to restore the bridge to limited use after the contractor sets up its rigging,” Keiser said. The limited use would involve establishing a narrow single lane around the construction operation to allow pedestrians, horse-drawn buggies, and vehicles weighing no more than five tons to cross the bridge. The direction of traffic through the single lane would be controlled by flaggers or possibly temporary traffic signals. “We’re very sensitive to the hardship that this bridge closure creates for many travelers,” Keiser explained, “and if we can manage to provide safe passage, although limited, that is a goal worth pursuing.”
Since discovering the crack in the girder on Monday afternoon, PennDOT engineers have been meeting and consulting with engineers from Michael Baker International, a consultant engineering firm, and J.D. Eckman to develop and evaluate repair options. Engineers from Lehigh University have also been retained to conduct testing of the steel material that will help determine what may have caused the crack.
Inspection of the bridge has also continued this week, and inspectors have identified other locations with minor cracks that are not uncommon in this type of structure. This information will need to be analyzed and repairs made to these locations as well.
Official detour routes have been established and signed for the bridge closure, directing traffic north to the Route 30 bridge between Columbia and Wrigthsville, or south into Maryland to the Route 1 bridge over the Susquehanna River at the Conowingo Dam.
Editor’s note: For your reference, the following labeling of the parts of a steel girder comes from www.SteelConstruction.info. Please note, however, that the girder on the Norman Wood Bridge is 14 feet high between the top and bottom flanges.