Utility Poles: Appendix 8

City of Huntsville, AL

Study of Roadside Object Crashes

The TSM Association of the University of Alabama completed a three-year study for the City of Huntsville, AL in 1988 (Turner, 1988). Rather than arbitrarily remove utility poles from the clear zone, the city wished to take a comprehensive approach to the problem. Studies were made to identify the best treatment for poles, trees, mailboxes, drainage devices, and other fixed objects.

The study involved 17,431 crashes that took place in Huntsville over a 30-month period. Single vehicle crashes with fixed objects in the roadside accounted for 1,254 (7.2%) of the total crashes and produced 13% of the injuries and 38% of the fatalities. The fixed object crashes are further detailed in Figure 1.

Figure 1:
Huntsville Roadside Object Crashes

Object Type Crash Number Visited in Field % Injuries % Fatalities
Poles 458 310 39.7 1.6
Mailboxes 94 19 5.9 1.2
Trees 177 90 43.0 1.3
Barriers 516 119 32.1 3.0

The crash reports on all 458 pole crashes yielded data such as time of day and day of week of the crashes. Field visits were made to 68% of the pole crash sites (the others could not be successfully located from crash reports). Information was collected for each site such as distance from the travel lane, roadway geometry, speed limit, road surface condition, pole size, etc. The reviews resulted in a variety of findings:

  • 90% of pole crashes took place within 10 feet of the traveled lane

  • The day with the greatest proportion of crashes was Saturday (21.3%). Friday followed with 16.1%.

  • 25.5% of pole crashes occurred on curves, but curved roads are estimated to comprise only 5 - 10% of Huntsville roads.

The 1988 report resulted in a number of recommendations for the city of Huntsville:

  • New poles should be placed a minimum of 2 feet behind the curb face when a parking lane is present.

  • New poles should be placed a minimum of 6 feet behind the curb face when a parking lane is not present.

  • New poles should be placed a minimum of 20 feet from the travel lane for speed limits less than 50 mph and 30 feet from the travel lane for speed limits greater than 50 mph.

Reference

D.S. Turner, "Summary of Recommended Strategies for Trees, Poles, Mailboxes and Barrier in the Clear Zone", TSM Association, TSM Report 118-88, University of Alabama, Tuscaloosa, AL, December 1988