Trestle
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| Trestle | |
|---|---|
| |
| Trestles are useful as approaches to bridges over marshes and shallows | |
| Ancestor | Beam bridge, clapper bridge |
| Related | None |
| Descendant | Viaduct |
| Carries | Heavy rail |
| Span range | Short |
| Material | Timber, iron, steel, reinforced concrete, post-stressed concrete |
| Movable | No |
| Design effort | low |
| Falsework required | No |
A trestle is a bridge that consists of a number of short spans, supported by splayed vertical elements and is usually for railroad use. Timber trestles were extensively used in the nineteenth century in mountainous areas and to traverse floodplains adjacent to rivers as approaches to bridges. These were typically constructed using peeled logs preserved with creosote as vertical elements and with bolted and spiked sawn timbers for bracing.
[edit] Many replaced in the mid Twentieth Century
Twentieth century construction eliminated much of the need for trestles by using far more extensive grading and tunneling. The trestle shown to the left is a modern structure with a long expected lifetime compared to a wood trestle. Being fireproof in this brushy location is also an advantage. One of the longest trestle spans created was for railroad traffic crossing the Great Salt Lake on the Lucin Cutoff in Utah. Replaced by a fill causeway in the 1960s, it is now being salvaged for its timber.
