Figure 1: San Francisco Bay Area express lane network
Janet Banner, Metropolitan Transportation Commission, and Christopher Hill, Mixon Hill, Inc., outline efforts to explore the use of IntelliDrive technologies in HOT lane applications
On 21 October last year more than 100 transportation professionals came together for a workshop, either in person or via a webinar, to discuss the potential role of IntelliDriveSM technologies in enhancing the operations of High-Occupancy Toll (HOT) lanes. The discussions focused on a White Paper, commissioned by theMTC is the transportation planning, coordinating and financing agency for the nine-county San Francisco Bay Area. It manages a range of technology projects intended to improve transportation system management in the region and has an active role in the national IntelliDrive programme.
In addition, the Commissioners of MTC serve as the
A grant received through the Urban Partnership Program (UPP), sponsored by the
HOT lanes are open to High-Occupancy Vehicles (HOVs) at no cost, while Low-Occupancy Vehicles (LOVs) must pay a toll or user fee. In general, HOT lanes become an option when the capacity of the managed lane is under-utilised by HOVs alone and for those drivers willing to pay a higher level of service can be provided in the managed lane compared to the adjacent general-purpose lanes. The higher level of service in the managed lane is maintained primarily by dynamically adjusting the pricing for LOVs.
HOT lanes are being implemented or considered in locations across the US. They present their own set of technical, institutional, design and operational challenges. One purpose of the White Paper was to consider how IntelliDrive systems and technologies can help address or mitigate the issues that have been identified by practitioners and researchers at the national level, as well as stakeholders in the Bay Area who will be responsible for the administration, operations, and enforcement of the express lane network.
The overall project is divided into two phases. Phase 1 covered the preparation of the White Paper and the October 2009 workshop. Phase 2 will be a demonstration of IntelliDrive technologies to support operations on a selected express lane facility in the Bay Area. An RFP for the demonstration phase is expected to be issued during the first quarter of 2010.
The White Paper identified nine use cases which were presented to the workshop participants and discussed in breakout sessions.
Toll collection
Tolling has been considered an IntelliDrive use case since the beginning of the national Vehicle-Infrastructure Integration (VII) programme. An essential component of any express lane implementation is the ability to collect tolls from LOVs that elect to use the express lane, while providing free access to the lane for those vehicles that meet the high-occupancy criterion.In general, a demonstration of Dedicated Short-Range Communications (DSRC)-based toll collection in the Bay Area will help advance the state of knowledge relating to this technology. Recommended test scenarios include use of: 5.9GHz-based DSRC equipment mounted on existing overhead structures, over the express lane alone, to determine the ability to differentiate vehicle location in a multi-lane situation; dual-mode 5.9GHz/915MHz readers and tags, with the equipment mounted on the existing overhead structures alongside existing 915MHz equipment to evaluate the compatibility with existing FasTrak operations; 5.9GHz DSRC equipment mounted on the side of the road, potentially in conjunction with high-accuracy positioning equipment onboard the vehicle, to evaluate the capability of detection down to individual lane level without the need for an overhead structure.
Dynamic pricing
A key aspect of a HOT lane deployment is the ability to provide dynamic pricing information to help drivers make decisions about their use of an express lane. DSRC could be used to allow drivers to calculate and see in-vehicle express lane usage fees for any destination they select. Drivers could determine their toll based on current charging rates at points well in advance of the express lane facility and be alerted if this toll has changed at any point prior to them entering the express lane (as demand increases or decreases and charging rates change accordingly). The demonstration could also provide an opportunity to assess other payment mechanisms, such as charging an individual trip to a credit or debit card, or deducting the fee from an onboard electronic purse instead of debiting an offboard account.Current express lane deployment plans in the Bay Area call for dynamic message signs prior to the ingress points on the lane. These signs can provide only limited amounts of pricing information, and may require drivers to estimate the fees they will pay based on the information presented. This may lead to conservative decisions by drivers when approaching the express lane.
In-vehicle account management
IntelliDrive can provide a communications path between a vehicle and an individual's FasTrak toll account. Questions remain regarding an individual's sensitivity to express lane toll pricing. It is possible that a driver will want to consider the available balance in their toll account prior to deciding to use an express lane. This application would allow a driver to obtain a real-time, in-vehicle update of his or her account status before making a decision.Back office toll processing
IntelliDrive technologies could provide a mechanism to reduce or eliminate certain back office toll transaction processing functions performed by BATA for both the express lane network and ultimately the toll collection system for local bridges. The demonstration would provide an opportunity to assess the potential to eliminate user accounts for toll transactions and instead initiate a real-time credit card transaction each time a vehicle passes through a tolling zone. The use of onboard DSRC equipment could facilitate the transfer of credit card information to the appropriate financial institution. BATA would then receive payment from the credit card company in a similar manner to other retail transactions.Mechanisms for the driver to provide their credit card information in-vehicle could include inputting details through a keypad or touchscreen. The test should include the use of contactless credit or debit cards and an onboard proximity reader, such as those being used by transit agencies in New York and Utah. This will create the opportunity to assess the availability and technical feasibility of a variety of in-vehicle equipment configurations.
Vehicle occupancy
Knowledge of the number of occupants in a vehicle is important to HOV compliance and express lane toll charging. While IntelliDrive technologies may appear to offer solutions to this need, the challenges to this appear to be significant at present.In theory, data on driver and passenger seat occupancy exists onboard the vehicle for use in smart airbag systems. This data, if accessible, could be used to provide an automated count of vehicle occupancy. For the Phase 2 demonstration, vehicle occupancy data may not be easily accessible through the vehicle's OBDII port since it is used in a critical safety system. However, it may be possible that vehicle manufacturers would be willing to cooperate in a research project in this area.
Automated enforcement
Automated enforcement could be a desirable application in a HOT lane environment. However, it presents both technological and institutional challenges. At present, the California Highway Patrol must play a direct role in the enforcement of any HOV or moving violation in the Bay Area.Potentially, vehicle positions on the roadway could be tracked using high-accuracy positioning systems and moving violations involving vehicles crossing the buffer zone could be identified. The Phase 2 field test could be used to evaluate such positioning systems and could also further the work carried out in the VII Proof of Concept (see 'Positive feedback', ITS International March-April 2009, pp.NA5-NA6) on the use of commercial GPS solutions.
Probe vehicles
A probe data service has been considered a central application since the beginning of the VII program. With sufficient penetration of IntelliDrive devices, probe vehicles can provide a detailed picture of prevailing conditions on the roadway network.Probe vehicles can be used to measure vehicle speeds and travel times. The data can be used as input to various traveller information and transportation management systems. The information can also be combined with other probe information to create a richer data set. Probe vehicle data collection is a viable use case for the Phase 2 field test. The test should evaluate alternative communications technologies for gathering probe data.
Traveller information
Many types of traveller information can be accessed by the driver but the most relevant to HOT lane operations would be information providing real-time travel time differences between the express and general-purpose lanes. This information could help drivers decide whether they perceive sufficient benefit from using the express lanes.The demonstration could provide an opportunity to assess technological approaches for obtaining vehicle probe data, calculating travel times, and communicating information to and from vehicles. The demonstration could also allow an assessment of blending information from multiple sources to determine if this provides a richer set of travel time data. The demonstration provides an opportunity to answer questions on what information is most relevant to the express lane user.
Regional and corridor traffic management
Information that can be gathered from IntelliDrive-equipped vehicles can be used to support a variety of traffic management applications. Vehicles used as probes can provide data that can support active traffic management and corridor management even when they are not operating on an express lane, provided an appropriate infrastructure is available. Probe vehicles may be particularly beneficial on arterials where traffic monitoring infrastructure is typically sparser. However, the Bay Area Express Lane Network will not be extensive enough in Phase 2 field test for this use case.Use case recommendations
The White Paper recommended three use cases: toll collection; back office toll processing; and traveller information (which incorporated aspects of the dynamic pricing, in-vehicle account management and probe vehicle use cases). During the workshop, participants endorsed all of the suggested use cases, not just the three recommended. In particular, the workshop participants and other stakeholders strongly encouraged pursuing the vehicle occupancy use case as a topic that would be of significant benefit to HOT lane operations. Based on the White Paper and the input from the workshop, MTC is currently considering which use cases are most desirable to carry forward into Phase 2.Phase 2
The purpose of the Phase 2 demonstration project will be to establish the technical, operational, and institutional viability of recommended uses cases based on selected IntelliDrive technologies for supporting HOT lane operations. Much will be learned from the demonstration that will inform future deployment decisions in the Bay Area, as well as provide input and direction to the national IntelliDrive agenda.Based on what has been learned in the development of the White Paper and input from the workshop participants, it is believed that there will be strong potential for the deployment of a viable IntelliDrive-based solution for HOT lane operations at the conclusion of Phase 2. There will also be opportunities for continuing development for the deployed system in the future. For example, the system may be enhanced as technologies improve and automated enforcement becomes practical or as the initially deployed system develops to support broader regional traffic management applications.
