Truck-Only Lanes


What are truck-only lanes? Truck-only lanes are lanes designated for the use of trucks. The purpose of truck-only lanes is to separate trucks from other mixed-flow traffic to enhance safety and/or stabilize traffic flow.

Are truck-only lanes common in the U.S.? No, very few truck-only lanes exist. Most states restrict trucks to certain lanes, but also allow all vehicles to use the same lanes.

Does California have any truck-only lanes? Yes, California has two truck-only lanes and others under consideration:

  1. Northbound and southbound I-5 in Los Angeles County at the State Route 14 split. Looking in the northly direction, the truck lanes begin as two roads: NB at LA County postmile C043.925 and SB at C043.899. The NB and SB roads join at postmile C044.924 and continue together up to postmile C046.351. The total lengths are 2.426 miles (NB) and 2.452 miles (SB). The purpose of these truck lanes is to separate slower moving trucks from the faster general traffic on the grade. After constructing the new I-5 alignment, the original alignment was used for the truck-only lanes. This truck-only facility has been in place for about 30 years.
  2. Southbound I-5 in Kern County at the State Route 99 junction near the Grapevine. This truck lane begins on Route 99 at Kern County postmile L000.629 (the equivalent of I-5 postmile R015.838) and ends on I-5 at postmile R015.492. The total length is 0.346 miles. The purpose of this design is to place truck merges further downstream of the automobile traffic merge of I-5 & 99.

Are trucks required to travel in truck-only lanes? Yes. Black and white signs direct trucks to use truck-only lanes. Black and white signs are enforceable.

Can passenger cars travel in truck-only lanes? Green guide signs encourage passenger cars to continue travelling in the main travel lanes and not use the truck-only lanes. However, since green guide signs are not enforceable, passenger cars are not prohibited from using truck-only lanes.

Southern California Feasibility Study

Has California ever studied truck-only lanes? Yes. In February 2001, the Southern California Association of Governments (SCAG) completed a feasibility study report (FSR) on exclusive lanes for commercial trucks. "Trucks" were defined as vehicles having three or more axles. The study focused on State Route 60, from I-710 to I-15, a distance of approximately 38 miles.

How was the route evaluated? SR 60 was evaluated for number of lanes, cross-sections, adjacent land use, over- and undercrossings and their clearances, and right-of-way.

What strategies were considered? Based on the above characteristics, three main strategies were considered: (1) allowing trucks to share the HOV lanes at limited time periods, (2) adding truck lanes to the freeway at grade, and (3) adding lanes above the freeway grade. The HOV lane option was dropped due to a number of barriers, including legal and funding obstacles.

What was the conclusion? The FSR recommended combining the two non-HOV strategies, with at-grade truck lanes built where feasible, and above-grade mixed-flow lanes built where right-of-way acquisition would be difficult. Above-grade lane sections should be kept to a minimum due to safety and operational considerations, as well as higher construction costs. Trucks would always operate at grade for safety.

By what criteria can truck lanes be selected? The FSR included a literature review which revealed that exclusive truck lanes were the most plausible for congested highways where three factors exist: (1) truck volumes exceed 30 percent of the vehicle mix, (2) peak hour volumes exceed 1,800 vehicles per lane-hour, and (3) off-peak volumes exceed 1,200 vehicles per lane-hour.