‘Bridge Slide’: Big Move Comprised of Tiny Movements

7-22 Bridge being moved onto new supports

7-22 Hydraulic pistons pulling threaded rods

Photos show the new bridge span before (above) and after (below) it was moved into final position in the middle of newly-cast concrete pieces. The old bridge span — which was to the right (north) of the new one — was dismantled and lowered to the ground. Using hydraulic rams and threaded steel rods (above), project engineers then moved the deck about 20 feet in order to center it on the supports.

7-22 4 Girders moved into place

During June and July, working two 12-hour shifts, SEPTA’s Crum Creek Viaduct repairs proceeded apace toward the anticipated completion and reopening of the bridge — and SEPTA rail service west of Swarthmore — in September.

If you make the trek (or send a camera drone) to view the project now, you will see a single concrete deck sitting on new steel girders, supported by four new concrete piers, between two new concrete abutments.

These supports were built under the existing structure of the rail bridge (parallel and to the north of the new structure) which had carried trains across the Crum from the 1980s through June 19, Following removal of that old bridge deck and catenary wires and towers, the new girders and deck sections were moved from the south edge to the center of the piers in a complex hydraulically-assisted process SEPTA called a bridge slide.

The Crum Creek Viaduct team reported on project progress: “The new Crum Creek Viaduct bridge slide began in the morning on Friday, July 8, and was completed on Saturday, July 9. In addition to the new bridge being placed, precast concrete for the pedestrian tunnel were set last week. Webcams are live on the project website— www.crumcreekviaduct.com — where you can also see a time lapse video of the new bridge sliding into place.” If you like big projects, the July 8 footage is required viewing.

7-22 Pistons retracted, tightening nuts

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