Mid-America Transportation Center


Date of this Version


Document Type



MwRSF Research Report No. TRP-03-165-07


Report No. TRP-03-165-07


Dynamic impact testing of W152x13.4 (W6x9) steel posts at various embedment depths has been detailed, and the results stated. A total of 17 bogie tests have been performed on a 2:1 slope, with post lengths varying from 1,829 mm (6 ft) through 2,743 mm (9 ft). A total of four bogie tests were performed on level terrain using 1,829-mm (6-ft) long steel posts at two different impact speeds. For each bogie test, raw acceleration data, obtained from accelerometers, was filtered and then force-displacement and energy-displacement graphs were plotted. From the energy-displacement graphs, the average post-soil forces were calculated for a 381-mm (15-in.) displacement at the center rail height. Post-soil forces were then compared to the required post capacity of 28.5 kN (6.4 kips), including energy dissipation characteristics, for the MGS placed on level terrain. From these comparisons, a recommended post length was selected for standard post spacing. A 2,743-mm (9-ft) long post with a 1,930-mm (76-in.) embedment depth was found to best meet the post requirements, while providing an average force of 28.42 kN (6.39 kips). As such, this post configuration was recommended for evaluation using computer simulation modeling.