General Guidelines
Part-time High-Occupancy Vehicle (HOV) Lanes:
Some lanes are restricted to carpools only during high-use commute hours. It is legal for single-occupant vehicles to use the HOV lanes if it is outside those HOV hours of operation. Signs will be posted along the HOV lane telling you when the lane is restricted to carpools only. These part-time HOV lanes are most common in northern California.
High-Occupancy Toll (HOT) Lanes:
These freeway facilities are also called "Express Lanes" and allow single-occupant vehicles to use the HOT lane by paying a toll electronically (with a FasTrak transponder or by using a Prepaid ExpressAccount). Some HOT lane facilities have a One-Time-Toll feature. Most HOT lanes allow carpools to use the lane for free (local signs will specify this and indicate if carpools must carry a FasTrak transponder). HOT lanes may not be used by vehicles restricted to a 55 MPH speed limit. An example of a HOT lane is the Sunol Grade on Interstate 680 in the San Francisco Bay Area.
HOV Lane Striping:
Do not cross solid, double lines whether they are white or yellow! If you are entering or exiting an HOV lane, you must change lanes only where there is a designated area or where you are crossing a single dashed line (white). In all cases, you must change lanes safely. For details, see the California Vehicle Code, Sections 21655.8 and 21460.