Mobile Table Test

Lane Departure CountermeasuresHighest Speed Impact (mph)


Other Crash Impacts1


Usage Within IowaIowa-Specific Guidance
Chevrons/signs/oversized chevrons
chevrons-1.60.75 to 0.96N/A$commonrefer to MUTCD
chevrons/warning signsN/A0.56N/A$commonrefer to MUTCD
oversized chevronsN/AN/AN/A$occasional
On-pavement markings
on-pavement curve sign-7N/AN/A$limited
Vertical treatments
post mounted delineators-80.70 to 0.80N/A$limitedrefer to MUTCD
conspicuity for chevron posts-2.2N/AN/A$limited
Dynamic speed feedback signs
DSFS on curves-7.90.93 to 0.95N/A$$limited
Longitudinal rumble strips
centerline rumble stripsN/A0.67 to 0.91-25 to -37%$$$occasional
shoulder rumble stripsN/A0.79 to 0.90-8 to -70%$$$common
edgeline rumble stripesN/A0.50 to 1.30N/A$$$tested
Roadway treatments
paved shoulderN/A0.81-8%$$$widespreadSection 3D-6 Iowa Design manual
Safety EdgeN/A0.94$$occasionalSection 3D-6 Iowa Design manual
high friction treatmentN/AN/A-20 to -25%$$limited
Lane narrowing
wider edge linesN/A0.38-27%$no experience
Lane narrowing