Chain Requirement Levels and Traffic Control Definitions
R-1:
Chains or snow tread tires required. Snow tires must have a tread depth of 6/32" with a "M & S" imprint on the tire's sidewall.
R-2:
Chains required on all vehicles except four-wheel drives or all-wheel drives with snow tread tires on all four wheels.
R-3:
Chains required - ALL VEHICLES- no exceptions
R-1 and R-2 are the most common chain controls. The highway will often be closed before an R-3control is imposed.
C
Road Closed
S
Split Control - Chains or snow tread tire requirements are set at two separate points of the highway for different requirements. It is not uncommon to have R-1 conditions from point A to point B and R-2 conditions from point B to point C.
T
Truck Hold - During major storms when traffic flow is heavy, Caltrans may hold commercial tractor-trailer combinations at specific points below the snow line. These points typically are:
Eastbound I-80 at Applegate (east of Auburn, CA)
Westbound I-80 at Verdi,
Nevada (west of
Reno, NV)
