[1] Timber and iron trestles (i.e. bridges) were extensively used in the 19th century, the former making up from 1 to 3 percent of the total length of the average railroad.
Timber trestles remain common in some applications, most notably for bridge approaches crossing floodways, where earth fill would dangerously obstruct floodwater.
One of the longest trestle spans created was for railroad traffic crossing the Great Salt Lake on the Lucin Cutoff in Utah.
[citation needed] Many wooden roller coasters are built using designs similar to trestle bridges because such a structure can be strong and support a high track path while using a relatively small amount of material.
Such wooden coasters, while limited in their path (not supporting loops), possess a certain ride character (owing to structural response) that is appreciated by fans of the type.
[4] The floodway of the Bonnet Carré Spillway in St. Charles Parish, Louisiana, is crossed by three wooden trestles each over 1.5 miles (2.4 km) in length.
At the top of the trestle, rolling stock (typically hopper cars) open doors on their undersides or on their sides to discharge cargo.
[5] In the United Kingdom, timber trestles were relatively short-lived as a structural type, one of their major uses being to cross the many deep valleys in Cornwall on the spinal rail route through the county.
The former, built in 1867, carries trains on the heavy rail Cambrian Coast Line travelling from England via Shrewsbury to the various small towns on Cardigan Bay.