Bridge No. 1276, the Sideling Hill Creek Crossing

A deck plate girder bridge for a Model Railroad Layout

The westward expansion of the Western Maryland Railway, beginning with the Cumberland Extension, was one of the last new mainlines constructed during the period of extensive growth among U.S. railroads in the period from the Civil War to World War I. It represents the height of railroad civil engineering at the beginning of the 20th Century. Employing modern materials and steam-powered construction equipment, engineers designed and built a railroad with six major bridges, three tunnels, and extensive earthworks to achieve low grades through rugged terrain.

The Cumberland Extension was extraordinarily expensive to construct, and due to travelling through sparsely-populated areas, proved difficult to make profitable. Nevertheless, the Cumberland Extension operated for seven decades, and despite struggling to make money on its western divisions, during the 1940s and 1950s, the WM earned its reputation as the Mid-Atlantic region’s railroading showpiece.

Bridge No. 1276, the Sideling Hill Creek Crossing is small by comparison with some of the other bridges on the Cumberland division, but that small size makes it perfect for inclusion on a model railroad.

Bridge No. 1276, Sideling Hill Creek Crossing, is a 145′-long bridge consisting of two deck plate girder spans carrying a single track on a slight curve, nearly 50′ above the creek bed.

The survey of the bridge for the Historical Engineering Record describes the structure:

The outside of the curve faces away from the river and up Sideling Hill Creek. Concrete abutments and an intermediate pier support the spans, each of which consists of two parallel plate girder chords, l’-4″ in width, spaced across from one another on 8′-0″ centers.

The eastern span is the longer and deeper of the two, at 95′-0″ in length and 9′-3 1/4″ in depth. There are a total of eight panel points on each girder of the longer span. The plates are joined by narrow plate steel gussets and reinforced by vertical, back-to-back, steel L sections at the joints. Additional angle steel reinforcing members occur at intermediate points within each panel. There are two 10′- 10 1/4″ panels at each end of each girder, divided into thirds by two intermediate reinforcing angles. In the center of the span there is a panel 14′- 4″ in length, and on either side, between the center panel and the end panels, are four 13′- 6″ panels, two on each side of the center panel. The center three panels are divided in two by a single angle reinforcement, while the ones adjacent to each end panel are divided into thirds.

The lateral members of the horizontal truss webbing at the tops and bottoms of the girders are joined to the girders by way of gussets attached to the girder flanges at each panel point. Diagonal members are also attached to the same gussets on the north side of the span and attached to their own gussets on the south side in the center of each panel. The longer span’s eastern end sits on a roller shoe at the east abutment, which supports the bridge. The abutment has angled wings so that it can also serve as a retaining wall for the fill to the west of the bridge. The western end of the east span rests on a fixed shoe atop a stepped pier at the west bank of the creek.

Attached to the east span by way of a riveted butt joint and towering over the creek’s steep bank is the shallower, 50′-long west span. The opposite end of the span rests directly on the concrete west abutment in a cove between two concrete abutment wings that are perpendicular to the abutment face and whose tops angle down from the top of the abutment to the top of the surface upon which the bridge rests. This shorter span’s center line angles 13 degrees southward from the center line of the longer span to follow the track’s curvature.

The construction of the panels and the horizontal webbing on this span differs somewhat from the larger span. A single large gusset-and-angle-iron joint subdivided into nine distinct sections by individual angle steel reinforcing members, divides the span into two sections, which are tall and narrow near the ends and gradually widen toward the center. There are four panel points in the horizontal truss webbing with a lateral member at each. The two panels at the ends include two diagonals, while the center panel includes four without a lateral between the center two diagonals. These members are joined to the girder flanges in the same manner and orientation as in the long span and correspond to the locations of the vertical angle reinforcements on the girders.

Owing to its curvature, the outside rail was superelevated 5″ to induce some centripetal force onto passing trains that reduced the curve resistance and inertially induced lateral force at speed. Wooden, wedge-shaped spacers between the top flange of the outer plate girder and the ties created the superelevation. The intermediate pier at the joint between the spans is concrete and consists of a cap, slightly wider than the vertically-tapered section below it, which rests in turn on a bottom section with vertical sides. The east and west sides of the pier are parallel. In plan, the downstream face is perpendicular to the sides, while the upstream face has an equilateral 45° wedge to split the stream current. A 4″ piece of angle steel embedded in the concrete reinforces the upstream face.

Dimensions for the pier are as follows: 35′-7″ tall (from the water level to top cap), 9′ wide at the base, 6′-8″ wide at the top cap, and 34′-5 3/4″ maximum depth at the point at the base. East of Sideling Hill Creek, the railroad is on a cut-and-fill bench and crosses an approximately 300′-long fill before returning to the bench. A series of bench cuts through shale and other rock of substantial size – as high as 50′ or more — punctuate the landscape on the uphill side of the bed, particularly west of the still-extant concrete milepost 128.

This bridge would best be constructed out of sheet styrene and styrene architectural shapes available from manufacturers such as Evergreen. Completed to prototype specifications, it would be a center of interest on a portion of a model railroad layout near the viewer. If intended for a spot nearer the background, much of the interior bracing could be eliminated and it would still be a great scale bridge for your model railroad layout.

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