Evaluation of Devices for Improving Traction Control in Winter Conditions

During the winter months, motorists may encounter tire traction controls (or “chain control”) in the California mountain regions. There are three levels of tire traction control requirements in California. (1) Requirement One (R1): 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. (2) Requirement Two (R2): Chains required on all vehicles except four-wheel drives or all-wheel drives with snow tread tires on all four wheels. NOTE: four-wheel and all-wheel drive vehicles must carry traction devices in chain control areas). (3) Requirement Three (R3): Chains are required on all vehicles, no exceptions. California Department of Transportation (Caltrans), partnering with California Highway Patrol (CHP) and local law enforcement, have to ensure the safety of the motorists by enforcing the tire traction restriction conditions. New tire traction devices are emerging which Caltrans, CHP and local law enforcement are unsure if they meet the definition of tire traction devices as noted in the California Vehicle Code. The California Vehicle Code, Section 605 defines tire traction devices as follows: "Tire traction devices" are devices or mechanisms having a composition and design capable of improving vehicle traction, braking, and cornering ability upon snow or ice-covered surfaces. Tire traction devices shall be constructed and assembled to provide sufficient structural integrity and to prevent accidental detachment from vehicles. Tire traction devices shall, at the time of manufacture or final assembly, bear a permanent impression indicating the name, initials, or trademark of the assembling company or primary manufacturer, and the country in which the devices were manufactured or assembled in final form. According to the vehicle code, Caltrans and CHP will allow any device that claims that it is in compliance with the Vehicle Code. All of the vendors claim that their devices are in compliance while driving on snow, but Caltrans sets up the tire traction device inspection sites well below the snow line which leaves a few to several miles traveled with the tire traction control device on wet roadway surfaces depending on changing snow conditions. This research is to evaluate what technologies are available, create test procedures, and test various tire traction control devices.