Promontory Route Railroad Trestles, Trestle 790A, 11 miles west of Corrine, Corinne

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This trestle is one of many remaining Promontory Route railroad trestles which were originally part of the first transcontinental railroad route con- structed across the United States. These trestles represent good examples of a class of small utilitarian wooden trestles constructed throughout the coun- try during the latter half of the century. PART L HISTORICAL INFORMATION 1. Date of construction: 2. Railroad structure designation: 790A (milepost 3. Architect: Central Pacific Railroad Company 4. Original and subsequent owners: Central Pacific Railroad Company, Southern Pacific Transportation Company, 1884-present 5. Builders, contractors, suppliers: Central Pacific Railroad Company 6. Original plans and construction: Unknown 7.

Alterations and additions: deck replaced, other repairs or replacements 8. Comments: The and Bridge Inspection Books1 describe this trestle as an open deck structure measuring 80 feet long and 6 feet high. In there is a note that the stringers were in poor condition and that the ties were bad and needed replacement. In the book mere are notations that the deck was replaced in The book also shows that some cap beams may have been replaced in tie plating was done in and cap beams were replaced in four posts on a bent were replaced or repaired in It was considered in good condition in PROMONTORY ROUTE RAILROAD TRESTLES, TRESTLE 790A (TRESTLE HAER No. UT-64-D (page 2) PARTH. ARCHITECTURAL INFORMATION This trestle is the longest of all of those recorded on this portion of the line.

It is a very low five-span wooden framed trestle with four-post bents suggesting that only "light loading" (use of E-45 locomotives) of the trestle was proposed.2 The trestle deck is 81 feet 5 inches long and is 3 feet 6 inches high from water to bottom of rail. There are 12-by-12-inch cap beams resting on each bent, which in turn, have another shorter 10-by-12-inch beam resting on them. On top of these inch beams rest two sets of three 8-by-16-inch stringers running the length of the trestle. Each set of three stringers is bolted together with collared metal spacers to maintain a precise distance between them and each set lies directly beneath one of the rail locations. Railroad ties lie atop the two sets of stringers.

At one end of the trestle a wooden guard timber was noted atop the ties, a feature which acted as a tie spacer to help keep ties in place during derailments. The bulkheads at each end of the trestle are built at a 45 degree angle. They con- sist of 2-by-12-inch boards stacked on end and supported by one of the trestle bents under the deck and by 8-by-10-inch posts on the wings. There are two 9-inch Chevron gasoline pipelines running the length of the trestle and resting on the bent cap beams on either end of the trestle. In a large portion of the eastern part of the trestle was burned as a result of a fire started by Chevron welders who were doing pipe maintenance work. 1.

Southern Pacific Transportation Company, Salt Lake Division, Bridge Inspection Books and On file at the Southern Pacific Transportation Company, San Francisco, California. 2. >*&lter Loring Webb, Railroad Construction, Theory and Practice, New York: John Wiley & Sons, Inc., p. i PROMONTORY ROUTE RAILROAD TRESTLES, TRESTLE 790A (TRESTLE HAER No. UT-64-D (page 3) Location of Trestle 790A("D"). Taken from: USGS Public Shooting Grounds, Utah Quadrangle