SUMMARY: NHTSA is issuing this ANPRM following a July 10@ 2014 grant of a petition for rulemaking from Ms. Marianne Karth and the Truck Safety Coalition (petitioners) regarding possible amendments to the Federal motor vehicle safety standards (FMVSSs) relating to rear impact (underride) guards. The petitioners request that NHTSA require underride guards on vehicles not currently required by the FMVSSs to have guards@ notably@ single unit trucks@ and improve the standards' requirements for all guards@ including guards now required for heavy trailers and semitrailers. Today's ANPRM requests comment on NHTSA's estimated cost and benefits of requirements for underride guards on single unit trucks@ and for retroreflective material on the rear and sides of the vehicles to improve the conspicuity of the vehicles to other motorists. Separately@ NHTSA plans to issue a notice of proposed rulemaking proposing to upgrade the requirements for all guards.