$5.$ Calculate the changes in expected average crash frequency for

a$.$ Run off the road, Head on and sideswipe crashes

b$.$ Total crashes

CMF$*$number of crashes per year before treatment $=$ expected average crash frequency per

year with treatment

We will evaluate a $6$ mile segment of a two$-$lane rural highway segment using the CMFs in Part D of the

HSM$.$

AADT for year $2008=5,494$ vpd$.$

$-$Currently the segment has: $11-$feet lanes and $4-$feet paved shoulders

$*$Proposed is: $10-$feet lanes and $5-$feet paved shoulders and install centerline rumble strips.

$-$For this example, we need to identify and determine the CMFs to adjust for the differences in lane width,

shoulder width and install centerline rumble strips.

Proportion of impacted crashes: