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Wilburton Railroad Trestle Lake Hills Connector
The original railroad trestle spanning Mercer Slough was built in 1904 by the Northern Pacific Railroad as part of a spur connecting the Bellevue area with the major railroad center in Renton. The frame bents used to construct the original trestle were of untreated material. The rapid decomposition of the wood required the complete replacement of the frame bents in 1913, 1924, and 1933. When the structure was rebuilt in 1943-1944, about half was constructed with bents of preframe timber treated with Wolman Salts and the other half was built with creosoted pile bents. The deck was still sound and was re-used on the new structure. Because of the unstable material of the slough, it was determined that filling was not practical. In 1941, it was decided to re-drive the foundation materials and renew the frame bents using creosoted materials throughout, but the project was halted because it was impossible to secure a sufficient amount of creosoted material. Eventually, it was decided to use short creosoted foundation piles for half the structure, topped with Wolman-treated timber for the posts, sills, struts, and braces. The rest of the trestle was renewed with creosoted material in 1944. The present structure is on a detour belt line extending around the east side of Seattle, known as the Lake Washington Belt Line. This line became the property of Burlington Northern following a merger in 1970. It is used mainly for freight transportation. The railroad trestle relates to the study unit theme of transportation and is an extremely prominent structure that can be seen from many locations in the Wilburton/Mercer Slough area of Bellevue. |