A high-occupancy toll lane (HOT lane) is a type of traffic lane or roadway that is available to high-occupancy vehicles and other exempt vehicles without charge; other vehicles are required to pay a variable fee that is adjusted in response to demand. Unlike toll roads, drivers have an option to use general purpose lanes, on which a fee is not charged. Express toll lanes, which are less common, operate along similar lines, but do not exempt high-occupancy vehicles.
The HOT concept developed from high-occupancy vehicle lane (HOV) systems in order to increase use of the available capacity, as it was found that HOV lanes were underutilized compared to general purpose lanes.
Most implementations are currently in the United States. The first practical implementation was California's formerly private toll 91 Express Lanes, in Orange County, California, in 1995, followed in 1996 by Interstate 15 in northern San Diego. According to the Texas A&M Transportation Institute, as of 2012[update] there were 294 corridor-miles of HOT/Express lanes in operation in the United States and 163 corridor-miles under construction.
The first HOT lane implementation in Canada was along the Queen Elizabeth Way (QEW) freeway in Ontario. Existing high-occupancy vehicle lanes were redesignated as HOT lanes for a 16.5-kilometre (10.3 mi) stretch of the QEW between Oakville and Burlington. The initial system consisted of $180 permits valid for three months, though HOT lanes with electronic tolling infrastructure were announced as part of forthcoming expansions to Ontario Highway 427.
Some systems are reversible, operating in one direction during the morning commute and in the reverse direction during the evening commute. The toll is typically collected using electronic toll collection systems, automatic number plate recognition, or at staffed toll booths. Exempt vehicles typically include those with at least two, three or four occupants, those that use approved alternative fuels, motorcycles, transit vehicles and emergency vehicles.
The fee, which is displayed prominently at entry points to the lanes, is adjusted in response to demand to regulate the traffic volume and thereby provided a guaranteed minimum traffic speed and level of service.
The Los Angeles Metro ExpressLanes HOT system requires vehicles to be fitted with manually "switchable" transponders where the driver selects the number of occupants, based on which the appropriate fee is charged. California Highway Patrol officers have in-vehicle devices which display the declared occupancy of a vehicle, which they can verify visually and cite any driver(s) with fewer occupants than declared (and tolled for). The new system proved itself to be highly effective in reducing the rate of lane-use violations, with it falling to 40-50% of the violation rates of other comparable California highways, from more than 20-25% (nearly one out of four or five) to just 10% (one in ten). Other transportation officials in California took note of this, subsequently leading to the Bay Area officials of Alameda County to adopt a similar system for the (then) planned Interstate 580.
Implementation of these systems can be prohibitively expensive, due to the initial construction required—particularly with regard to providing access to and from the express toll lanes at interchanges. However, the long-term benefits—the decrease in delay to able motorists and increased funding for the transportation agency—may outweigh the costs. To offset costs of construction, many transportation agencies lease public roads to a private institution. As a result, construction may be partially or fully funded by the private institution, which receives all of the income from tolling for a specified period.
Because HOT lanes and ETLs are often constructed within the existing road space, they are criticized as being an environmental tax or "Lexus lanes" solely beneficial to higher-income individuals, since one toll rate is charged regardless of socioeconomic status and the working poor thus suffer greater financial burden, although some states offer tax deductions or rebates to low income individuals for toll payments. Supporters of HOT lanes counter with the fact that because HOT lanes encourage the use of public transit and ride sharing, they reduce transportation demands and provide a benefit for all. However, HOT lanes have demonstrated no guarantees in eliminating traffic congestion, bringing into question their fundamental usefulness aside from raising funds for private institutions and local governments.
High Occupancy Toll (HOT) lane infrastructure will be included in the construction work. A 15.5 km stretch of dedicated HOT lanes with electronic tolling in both directions on Highway 427, from south of Highway 409 to north of Rutherford Road, will open in 2021.