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In the face of growing urban congestion, the range of strategies to maintain and improve highway service is also increasing. The traditional approach has been the addition of general-purpose lanes. However, because of the high costs and impacts of creating new capacity, increasing attention is also being given to strategies that make the maximum use of existing highway capacity.
These strategies focus on both highway supply and demand. The most basic supply-side measure is the provision of additional roadway capacity. Given the environmental concerns and cost of adding new capacity, Departments of Transportation (DOTs) are also making increased use of Intelligent Transportation Systems (ITS) technologies to support improved operational efficiency on existing facilities by focusing on operational control and the provision of real time user information.
At the same time, transportation officials are using a range of demand management strategies to influence user demand and provide preferential services to certain vehicle types. One such strategy, High Occupancy Vehicles (HOV) lanes, reserves existing or new highway lanes for the exclusive use of car pools and transit vehicles. In some areas, DOTs are expanding HOV lanes into metropolitan area-wide networks. An additional management strategy uses variable prices on tolled facilities to attract motorists to lower priced off-peak times, thereby maintaining higher service level volumes during peak periods.
One of the most recent management concepts High Occupancy Toll (HOT) lanes combines HOV and pricing strategies by allowing single occupancy vehicles to gain access to HOV lanes by paying a toll. The lanes are managed through pricing to maintain free flow conditions even during the height of rush hours. The appeal of this concept is tri-fold:
The combined ability of HOT operations to introduce additional traffic to existing HOV facilities, while using price and other management techniques to control the number of additional motorists and maintain high service levels, renders the HOT lane concept a promising means of reducing congestion and improving service on the existing highway system.
With only four HOT lane facilities operating in the Untied States in 2002, decision makers may not have the familiarity necessary to recognize the potential of the concept and consider it in situations where it could be appropriate. This guide is intended to encourage further consideration of the concept by providing transportation professionals with information and insight gained from the nations initial experiments with HOT lanes.
HOT lanes are limited-access, normally barrier-separated highway lanes that provide free or reduced cost access to qualifying HOVs, and also provide access to other paying vehicles not meeting passenger occupancy requirements.
By using price and occupancy restrictions to manage the number of vehicles traveling on them, HOT lanes maintain volumes consistent with uncongested levels of service even during peak travel periods.
Most HOT lanes are created within existing general-purpose highway facilities and offer potential users the choice of using general-purpose lanes or paying for premium conditions on the HOT lanes.
HOT lanes utilize sophisticated electronic toll collection and traffic information systems that also make variable, real-time toll pricing of non-HOV vehicles possible. Information on price levels and travel conditions is normally communicated to motorists via variable message signs, providing potential users with the facts they need in order to decide whether or not to utilize the HOT lanes or the parallel general-purpose lanes that may be congested during peak periods.
HOT lanes may be created through new capacity construction or conversion of existing lanes. Conversion of existing HOV lanes to HOT operation is the most common approach.
As described above, the HOT lane concept combines two of the most effective highway management tools: value pricing and lane management. These techniques are defined as follows:
The use of pricing to moderate demand during peak periods is common in sectors such as power and air travel. Similarly, the concept of value pricing within the highway sector involves the introduction of road user charges that vary with the level of congestion and/or time of day, providing incentives for motorists to shift some trips to off-peak times, less-congested routes, or alternative modes. Higher prices may also encourage motorists to combine lower-valued trips with other journeys or eliminate them entirely. When peak period volumes are high, a shift in a relatively small proportion of trips can lead to substantial reductions in overall congestion levels and more reliable travel times.
Lane management involves restricting access to designated highway lanes based on occupancy, vehicle type, or other objectives. Preferential service is provided by limiting the number of vehicles on designated lanes to levels where a desirable level of traffic service can be maintained. Managed lanes are separated from general-purpose lanes either with pavement striping or physical barriers, with entry limited to designated vehicles only. The rationale for lane management is to maintain a superior level of service and attract use by eligible vehicles that would otherwise travel in the parallel general-purpose lanes during peak travel periods.
Lane management can encourage a range of vehicle-related policies including:
- Car pools and transit vehicles to encourage higher occupancy;
- Trucks to improve goods movement;
- Low emission vehicles (LEV) to improve air quality
- Vehicles equipped for electronic toll collection to improve operational efficiency; and
- Vehicles with other special designations.
HOT Lane Management Strategies
Several mechanisms may be used to manage traffic flows on HOT lanes:
Occupancy Requirements: Qualifying HOVs are allowed to use HOT lane facilities at no cost or at a reduced toll. HOVs are usually defined as vehicles carrying 2+ or 3+ persons.
Pricing Systems: In order to maintain superior traffic service conditions, toll levels are set to limit the number of users by willingness to pay. The fee structure may be fixed, varying by time of day, or dynamic, varying in response to real-time traffic conditions. In either case, higher tolls are charged during peak demand periods. Information on toll levels is conveyed to motorists through variable message signs located near entry points.
Toll Collection Procedures: In order to avoid the delays associated with manual toll collection, HOT lanes rely on electronic payment systems or paid monthly passes during test pilot periods. Therefore, only those vehicles equipped with a transponder tag or valid permit may use the lanes.
Vehicle Type: A range of management policies may be implemented related to vehicle type. Depending on local transportation goals, low-emission vehicles, motorcycles, emergency vehicles, transit vehicles, taxis, and/or trucks may be allowed to use a HOT lane, either at no cost or for a reduced fee.
Access Points: HOT lane facilities are normally separated from general-purpose travel lanes by physical barriers or lane markings. Access to the lane may be provided at intermittent points, but in many cases there may be only single entry and exit points. Barrier separation and the limited number of access points are important tools for managing traffic flows on HOT lanes.
The history of HOT lanes appears to have led to some standardization regarding physical configuration and operation of these facilities.
As experience with HOT lanes expands, there may be additional convergence, with new standards emerging for certain design and operational features.
It should also be noted that the physical configuration and operational policies of these facilities are markedly different.
While an increasing number of state DOTs are studying the HOT lane concept as a strategy to improve urban highway service, there are only four HOT lane facilities currently operating in the United States.
State Route 91 (SR 91) Express Lanes Orange County, California SR 91 Express Lanes are a 10-mile, four lane, HOT facility located in the median of an existing highway. Toll rates on the Express Lanes vary from $0.75 to $4.75 by time of day and day of the week. Customers must have a prepaid account and transponder to use the Express Lanes. Tolls for HOV2+ vehicles are reduced by 50 percent. The SR 91 Express Lane project was awarded on a concession basis to a private consortium, which financed, built, and operated the new lanes, using project revenues to repay its debt and derive profit. In April 2002 plans were put into place to sell the facility to the Orange County Transportation Authority (OCTA).
I-15 FasTrak San Diego, California The I-15 FasTrak involved the conversion of an underutilized preexisting eight-mile 2-lane HOV facility to a peak-period reversible HOT. The I-15 FasTrak program allows single occupancy vehicles to pay a toll ranging from $0.50 to $4.00 to use the HOT lanes normally reserved for vehicles with two or more occupants. Customers must have a FasTrak account and transponder to use the HOT lanes. HOV2+ vehicles may use the facility at no cost. The project is sponsored by the San Diego Association of Governments (SANDAG), the local metropolitan planning organization (MPO), which has earmarked a significant portion of the revenues derived from the HOT lane to fund transit improvements in the I-15 corridor.
Katy Freeway QuickRide Harris County, Texas The Katy Freeway is an existing highway with a 13-mile, 6-lane freeway with a 1-lane reversible HOV lane in the median which initially operated at HOV 2. The facility was heavily utilized and eventually converted to HOV 3 operation in order to reduce congestion. However, this change resulted in excess capacity on the facility during the peak periods. As a result, the QuickRide program was introduced, allowing HOV 2 vehicles to pay $2.00 per trip to use the facility during peak periods, while HOV 3+ vehicles continued to use the facility at no cost. Customers must have a QuickRide account, transponder, and windshield tag to use the facility.
Northwest Freeway (U.S. 290) QuickRide Harris County, Texas The Northwest Freeway connects the northwest suburbs of Houston with downtown, and has had a one-lane, barrier-separated, 15.5 mile, reversible HOV facility in its median since 1988. In November 2000 the Northwest Freeway HOV lane was converted to HOT use, and is operated in a manner similar to the Katy Freeway. The Northwest QuickRide allows paying two-plus carpools to use the lane only in the morning peak when three-plus occupancy requirements are in effect. From 6:45AM to 8:00AM, when the facility serves inbound traffic, three-plus occupant vehicle may use the lane for free, but two-plus vehicles must pay $2.00 to use the lane. HOV3+ vehicles may use the facility at no cost, while single-occupant vehicles are never allowed on the QuickRide lane.
HOT lanes have the potential to afford a variety of benefits to both motorists and transit users. While no strategy can be expected to substantially eliminate congestion, HOT lanes provide an important management tool with the potential to improve travel conditions for a meaningful segment of the driving public with a range of potential benefits:
Trip Time Reliability: Traffic volumes on HOT lanes are managed to ensure superior, consistent, and reliable travel times, particularly during peak travel periods.
Travel Time Savings: HOT lanes allow HOV and paying non-HOV motorists to travel at higher speeds than vehicles on congested general-purpose lanes.
Reduced Vehicle Hours Traveled (VHT): The addition of HOT options to an existing HOV facility may provide traffic service improvements on congested general-purpose highway lanes. These improvements also have the potential to draw vehicles off of other parallel routes and improve overall flows and speed levels in the corridor.
Revenue Generation: HOT lanes can provide an additional source of revenue to support transportation improvements such as the construction and operation of the lanes themselves, or to address corridor transit needs or other local demand management strategies. In areas with funding constraints, certain improvements might not be possible without the additional revenue provided by HOT lanes.
Transit Improvements: HOT lane revenues may be used to support transit improvements, and new HOT lane facilities provide faster highway trips for transit vehicles.
Enhanced Corridor Mobility: Improved trip time reliability, higher speeds, travel time savings, and possible transit improvements all lead to greater mobility at the corridor level.
Environmental Advantages: Compared to general-purpose lanes, HOT lanes may provide environmental advantages by eliminating greenhouse gases caused by stop-and-go traffic, and by encouraging people to use carpools and mass transit, thereby reducing the number of cars on the road.
Trip Options: In congested corridors with HOV facilities and transit service, HOT lanes provide SOV motorists with an additional travel choice: the option of paying for a congestion-free, dependable and faster trip.
Utilization of Excess Capacity: HOT lanes may provide an opportunity to improve the efficiency of existing or newly built HOV lanes by filling excess capacity which would not otherwise be used.
New Interest in Managed Lanes: By increasing the traffic carrying capability of HOV lanes, HOT lanes may make managed lane applications attractive in regions that would not otherwise consider them.
Remedy for Under-Performing HOV Lanes: In some areas there has been increasing pressure to convert under performing HOV lanes to general purpose use. HOT lane applications have the potential to increase the number of vehicles traveling on underutilized facilities and possibly reduce pressure to convert them to general-purpose use.
New Interest in Value Pricing: HOT facilities demonstrate the benefits of value pricing in transportation that may be transferable to a broader array of services.
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