CMF for Installing a Median Barrier Table 13-23

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CMF for Installing a Median Barrier Table 13-23

Postby gamparano » Fri Jun 22, 2012 1:31 pm

Table 13-23 of the HSM (which is on page 13-24 of the HSM) has these CMFs for median barrier:

Install steel median barrier: 0.65
Install cable median barrier: 0.71

The crash type is listed as "All types (injury)".

For injury crashes, one would expect that cable median barrier to have a higher CMF (more effective at preventing injury crashes) than steel median barrier. Are these values correct, or should they be reversed?
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Re: CMF for Installing a Median Barrier Table 13-23

Postby Mohamad Banihashemi » Thu May 09, 2013 7:45 am

It seems that these figures are from Table 1.15.3 of "The Handbook of Road Safety Measures" 2004 edition (page 351) and they are fine. Based on that Table Steel Median Guardrail will decrease the probability of injusy by 35% (with 95% confidence interval of -43 to -26) and Wire Median Guardrail will decrease the probability of injusy by 29% (with 95% confidence interval of -40 to -15). The studies are from 2001 and before. There might be newer studies that show Wire is better than Steel but I am not aware of them or there might be newer configuration of Wire (Cable) barrier that have better performance.
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