INSIDE THE DOT
South Dakota Department of Transportation
Crash Testing of Dual Cedar Posts
Dan Johnston, SDDOT
1/1/1900 - 1/1/1900
The SDDOT has previously drilled 4" X 6" Cedar posts for breakaway applications because of results from crash testing of 4" X 6" Southern Pine posts. After having successfully crash tested single undrilled 4" x 6" cedar posts (SD93-04), it is desired that additional crash testing be done to gain approval for dual undrilled posts (2 posts within a 7 ft width).
1 To determine whether dual undrilled 4" X 6" cedar posts may be used in breakaway applications.
1 Perform crash test with an 1800lb (820 kg) vehicle travelling at 20mph (35 kph) impacting a dual 4" X 6" western red cedar sign post embedded in weak soil. (see attached configuration). Test procedures shall be in accordance with NCHRP Report 350, and acceptance criteria shall be that found in section 7 of the AASHTO Standard Specifications for Highway Signs, Luminaires and Traffic Signals. After test is completed, notify panel verbally and provide brief written test report.
2 If test in task one fails, contact research panel for further direction to rerun 20mph (35kph) test in standard soil. If test passes, go to task three.
3 Perform crash test at 60mph (100 kph) in standard soil, using the above parameters. Whether this test passes or fails, go to task 4.
4 Prepare and submit final report and executive summary including test methods, data, findings, analysis, recommendations and any other pertinent information necessary to approve or reject design.
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