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:

Calculating CMF for treatment $1$: changing lane width

a$.$ Step $1$: Calculate the CMF for the existing $11$ feet wide lanes for

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

ii$.$ Total crashes

b$.$ Step $2$: Calculate the CMF for the proposed $10$ feet wide lanes for

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

ii$.$ Total crashes

c$.$ Step $3$: Calculate the treatment CMF for changing lane width for

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

ii$.$ Total crashes