Design methods being developed for uncased crossings of high-pressure gas pipelines use impact factors to account for the increase in live load response due to the effects of vehicle speed, track stiffness, vehicle suspension characteristics, or irregularities in the running surface. Field experiments to measure impact effects were conducted on an instrumented pipeline 36 in. (914 Mm) in diameter buried 5.75 Ft (1.75 M) below the facility for accelerated service testing track at the transportation test center in pueblo, colorado. Ranges of vehicle speeds and surface geometry conditions were investigated, and impact factors based on measured pipeline strains were determined. The results indicated that train speeds of 5 to 40 mph (8 to 64 km/hr) had a relatively minor influence on impact response, whereas changes in surface geometry resulted in a range of dynamic pipeline strains, with the maximum values nearly 1.6 Times larger than previously recorded under baseline operating conditions. This paper appears in transportation research record no. 1315, Culverts and pipelines: design, monitoring, evaluation, and repair 1991.
Abstract