What does RAMP mean on an oversize permit?

Ramp. An on- or off-ramp. Permits list ramps as their own row, often with their own short mileage.

Also printed as RP RAMP, ON RAMP, OFF RAMP.

On real permits

PrintedMeansState
GATEWAY DR W/B ON RAMPThe westbound on-ramp from Gateway Drive, where the route startsCalifornia
I-70 Ramp NorthThe ramp from I-465 onto I-70Indiana
US-45 RampThe ramp from I-22 onto U.S. Highway 45Mississippi
I-25 RampThe ramp onto Interstate 25. Ramps get their own row with their own short mileage.New Mexico
I-70 RampThe ramp onto Interstate 70. Ramps get their own short row.Ohio
I-405 RampThe ramp onto Interstate 405. Ramps get their own short row.Washington

Decode a whole route line