4.1.8.7 Open Culvert

Prototype Information

A culvert is a transverse drain or waterway under a road or railroad. Culverts differ from a bridge in that a culvert is an opening through the roadbed with a depth of roadbed over it, whereas a bridge replaces an entire section of roadbed. 

Engineering. 

Open culverts are used where the track crosses small rapid streams which wash down large quantities of drift, and the track is close to the bed of the stream. Formerly, it was much the practice to construct such culverts by merely laying two stringers across walls of timber, or masonry, to carry the rails. The open top of the engineering design was to make the culvert  accessible for cleaning out when it becomes filled or obstructed. The negative was that a derailed car or truck running into the culvert can wreck the train.

There are three basic types: 

1) Beam, 

Trough stringers. This stringer is formed by riveting two 12-in. channels (placed back to back) to a third channel of same width placed open side downward between them. The rail rests upon 4x12x12-in. creosoted blocks placed in the. trough, the depth of which is such as to bring the top of rail fill with the top of the stringer. The fastening for the rail consists of clips, with bolts passing through block and bottom channel. For 15-ft. spans the sides of the trough are formed of channels each weighing 50 lbs. per foot, and for 12-ft. spans the channels weigh 30 lbs. per foot; the bottom channel used in either case weighs 30 lbs. per foot. At the ends the 1:1 stringers are anchor-bolted to 12x12-in. caps with bearing plates 1 in. thick between the two.

XXXXX.  On the Southern Pacific system of the same road a similar method of support is employed in crossing irrigation ditches, the stringer supporting each rail in this case consisting of two pieces of T-rail 5 ft. long, spaced just far enough apart to permit the flange of the track rail to lie in the opening between their webs. The flange of the track rail fits closely under the heads of the two stringer rails and is supported upon bolts passing through the webs of the stringer rails at intervals of 18 ins. In some places there are as many as three consecutive spans of these T-rail stringers.

Modeling Information

 The WWSL

The WWSL models several type of beam culverts:

• A timber beam culvert located on the OPLC main tracks at Camp 1.
• A rail top culvert with thin floor on the OPLC main tracks at Camp 1.
• A timber beam culvert located on the OPLC the north leg of the Wye track at Reload.

References