Recent environmental concerns related to the use of herbicides and efforts to reduce the cost and hazard of hand mowing around guardrail posts has led many districts to place either a concrete or asphaltic mow strip around the posts. However, the stiffness of the confining material around the guard fence posts can compromise the crashworthiness of the guardrail system. Under this project, methods and guidelines for installing strong-post guardrail in pavement mow strips were developed. Numerical simulation was used to evaluate guardrail performance with different levels of post confinement and select a design for full-scale crash testing. Full-scale crash tests of both wood and steel post guardrail systems were successfully performed. The mow strip design consists of leave outs formed around the soil embedded posts. The top 5-inches of the leave outs are backfilled with a low-strength grout mixture that resists vegetation growth and can crush and permit post rotation during an impact. The Federal Highway Administration (FHWA) issued guidance based on the results of this research.
N.R. Seckinger, A. Abu-Odeh, R.P. Bligh, P.N. Roschke. Performance of Guardrail Systems Encased in Pavement Mow Strips. Journal of Transportation Engineering, Vol. 131, No. 11, November 2005, pp. 851-860.