Automated Bus Rapid Transit (ABRT) Demonstration


Note: The following is the handout prepared for use at a demonstration of ABRT, held in August of 2003, in San Diego, California. For a full report on the results of the demonstration, see PATH Demonstrates Automated Bus Rapid Transit Technology, by Steven Shladover.


Automated Bus Rapid Transit (ABRT) may be viewed as the integration of several elements:

• Precursor systems such as transit information and operational improvements to enhance fleet management and provide more accurate and timely information to passengers, and collision warning systems to improve bus safety

• Bus Rapid Transit (BRT) service innovations in fare collection procedures, station design and location, and more attractive vehicle designs

• Automatic precision docking to enable buses to stop immediately adjacent to a loading platform, providing passengers with quick and easy boarding and alighting, even for those whose mobility is impaired

• Automated bus operation on segregated busways, providing rail-like ride quality while minimizing the needed right-of-way width.

How will it function and with what technologies?

Bus transit automation will consist of automation functions and complementary elements (advanced public transportation systems) and include certain design attributes.

Automation functions:

• Precision docking

• Lane keeping

• Automated speed and spacing control

• Maintenance yard operations

Complementary elements:

• Collision warning (forward, side, and rear)

• Vehicle diagnostics warnings

• Transit management center operations

Trip information for travelers at stops, stations and on-board buses

Electronic fare payment and pre-pay systems

Passenger counting systems

Traffic signal priority systems

Supporting design attributes:

• Bus design changes (low floor, wide doors)

• Bus stop/station design

• Infrastructure (bus bulbs, queue-jumpers, dedicated lane, check-in/check-out system, vehicle-roadside - communications)

• Bus components (electronic throttle, brake, and steering control)

Why demonstrate automated buses now?

The earliest deployments of automation technologies in road vehicles will likely be on heavy vehicles—buses and trucks—operating on their own special rights-of-way because:

• It’s easier to develop and acquire rights-of-way for public purposes like transit service

• In some cases, buses already operate on separate facilities, which could, if demand warranted, be switched over to automation

• Costs of the technologies are a smaller percentage of total bus costs and buses are used much more intensively so these costs are amortized faster

• Benefits in travel-time reduction, trip reliability and safety can be translated more directly into cost savings and revenue increases than for private passenger cars

• Customized, small-lot production of vehicles makes it possible to introduce automation technologies into the bus production process faster than for automotive mass production

• Packaging of new technological elements is easier on buses than on passenger cars

• Buses already have more onboard electronic infrastructure (such as data buses and electronic engine controls) to use as a foundation for more advanced capabilities than passenger cars

• Maturing technologies can be used more safely by professionally trained bus drivers on professionally maintained buses than by the general public on passenger cars that may not be well maintained.

Who benefits and how?

• Transit properties

• Bus drivers (employees)

• Bus passengers (general public)

• Infrastructure owners and operators

The overall benefit will be an improved level of people movement, mobility, and quality of service. More specifically:

For Transit Properties

• Reduced dwell time at bus stops for loading and unloading of passengers and avoiding need for

maintenance-intensive wheelchair ramps by use of precision docking with low floor buses

• Precision docking at bus stops should help reduce tire scuffing against the curb, resulting in reduced

wear-and-tear on the bus’s tires and corresponding maintenance costs

• Rail-like line-haul service at a much lower capital cost

• Narrower rights-of-way and structures for busways are possible with the use of automated steering/lane keeping

• Potentially reduced operating costs (labor, fuel and vehicle productivity) for the automated portion of the bus trip (line-haul)

• Facilitating maintenance operations and saving yard space and labor, (i.e., reducing costs), ordinarily used to move buses through routine maintenance processes

• Greater vehicle and passenger lane-capacity, by enabling buses to operate at shorter headway than under manual control

• Reduced fuel consumption and emissions for buses that can operate in automated platoons with small enough separations that aerodynamic drag can be reduced

• Potential safety improvements should have direct benefits in terms of reduced insurance costs and less time lost from buses taken out of revenue service while being repaired for crash damage

• Increased ridership is a collateral benefit that could result from the cumulative effect of the previously stated benefits

For Bus Drivers

• Automating precision docking at bus stops will make this operation easier and less stressful

Automated line-haul operations reduce workload and stress

For Bus Passengers

• Reduced travel time can result from having automated bus travel on a dedicated lane

• Improved bus stop arrival reliability

• Enhanced access to and from buses for mobility impaired passengers and reduced time for -loading and unloading of all passengers from bus stop - precision docking

• Smoother travel for passengers and increased passenger riding comfort

• Flexibility to perform in “dual mode”: collection and distribution, and line-haul portion (even with

intermediate stops). This may reduce need for passengers to make transfers, allowing

passengers to remain on same vehicle for entire “door-to-door” service. The bus would “transfer”

between a local neighborhood collector/distributor and a line-haul rail-like mode of operation.

For Infrastructure Owners and Operators

• Permitting operations on narrower rights-of-way (reduced lane widths), thereby saving on land use and physical infrastructure costs


What are some of the challenges facing  successful deployment?

Solution strategies are currently being sought for these and other challenges.

The transit industry may have concerns over the complexity and reliability of new technologies associated with bus transit automation. These concerns may influence the acceptability of technological changes that could potentially impact:

• Role of the driver (driver training, salaries, and work rules, additional driver responsibilities)

Maintenance cost and complexity

• Safety

• Liability (changing risk and responsibility assignment).

Large-scale public transportation projects have the potential for influencing travel patterns and surrounding land uses. Automated bus transit operations, intended to replicate high-level transit service, (e.g., rail transit), though more flexible, may raise concerns over:

• How they fit into a region’s overall transportation plans to be considered as a credible alternative for
regional public transportation investment

• How their inherent flexibility over rail transit may be perceived instead as a lack of permanence and inhibit potential developers from investing heavily along such transit corridors.

Will bus transit automation cost more?

There will be incremental costs associated with the use of bus automation technologies: additional electronic equipment installed and maintained on buses and busways and some additional protection of the busways to prevent intrusion by pedestrians, animals, unauthorized vehicles and debris.

Additional bus equipment is likely to consist of:

• Electronically controlled brake actuator (but this may soon become standard equipment associated with anti-lock braking anyway)

• Electronically controlled steering actuator

• Lateral-position sensing system

• Forward ranging sensor system similar to - commercially available sensors for adaptive cruise control systems

• Vehicle-to-roadside and vehicle-to-vehicle data communications systems, which could build on existing and impending traffic signal priority system and DSRC technologies

• Collision warning sensor systems, which are already available for some vehicle applications and are under commercial development for others

• Onboard control computer similar in power to standard personal computers

At early stages of development, the total costs of these systems are likely to add no more than 5% to 10% to the cost of a new transit bus, and over time those Incremental costs should decrease by another factor of 4 or 5. It is important to consider these additional cost elements in the context of the costs of providing higher quality transit services by other means, such as light or heavy rail transit systems. In the context of such costs, these incremental costs are negligible.

How do we get from today’s bus transit system to automation?

The specific development and deployment sequence will likely vary by location, depending on local and regional needs and constraints, so some locations will undoubtedly be able to make faster progress than -others. However, a generic sequence can be defined, -building on technologies already available or nearly available and then combining additional technologies and service elements in building-block fashion to achieve increasing levels of capability.

There are existing and currently emerging technologies commercially available today in at least one major sector of the world (Europe, North America, or Asia/ Pacific) for at least some vehicle classes or for specialized applications. They are:

• Forward collision warning

• Lane-departure warning

• Adaptive cruise control (ACC)

• Vehicle-roadside communication

Transit forward collision warning is being developed now by PATH for the San Mateo County (California) Transit District (SamTrans) under the sponsorship of the Transit Intelligent Vehicle Initiative.

Special capabilities can be added to transit buses with moderate levels of development and deployment costs:

• Vehicle-vehicle data communication for cooperative adaptive cruise control (CACC)

• Low-speed precision docking of buses at stops

• Automation of bus movements through maintenance facilities

A next level of deployment includes protected-lane opportunities, particularly useful in locations where there are strong needs for enhanced transit services and/or where the right-of-way can be made available. In these locations, the operating agency can set aside a separated, protected lane for transit use. It then becomes possible to implement automatic steering control safely, permitting use of a narrower lane and relieving the bus driver of the steering responsibility.

Integrating a combination of these elements can form the basis of an initial operational scenario for bus transit automation, such as a pure line-haul run with few intermediate stops. Passengers could be collected from their origin locations at normal local bus stops, where the bus would be driven manually (except for the assistance of precision docking at stops). At the entrance to the protected busway or bus lane, the driver would switch the bus to automated operation and it would continue to operate automatically until it reached the busway’s destination end. There could be intermediate stops along the automated busway, where the bus would operate exactly the way automated metros or automated guideway transit systems do now. At the end of the automated busway, the driver would resume manual control of the bus and could take the passengers to their desired local bus stops. Through this kind of “dual mode” operation, the automated bus provides the collection and distribution flexibility of conventional buses and the line-haul efficiency and service speed of conventional rail transit, while saving passengers the inconvenience and time associated with transfers. This is the great service advantage automated buses can provide.

Over the longer term, with further advancements:

• Access to the ABRT lane could be provided to suitably equipped vanpools and then carpools

• Buses or vans could be coupled together more closely with their counterparts to form platoons, increasing capacity while reducing drag, to save fuel and reduced emissions

• Entry maneuvers could be automated with the addition of more sophisticated vehicle-roadside communication

• Higher-level management functions could be implemented to serve a network of connected ABRT lanes. These could indeed become the precursors to an automated highway network.

Functions to Observe In the Demonstration

Precision docking, in configurations suitable for terminal or station (in-line) or at conventional arterial bus stops (full lane change)

Very small gap between platform and bus entrance

Accessibility for mobility-impaired passengers

Reduced stress for driver

Reduced likelihood of scuffing tires at curb

Smooth and easy transitions between normal manual driving and automation functions

Simple user interface

Easy resumption of driver control when needed

Smooth control transitions

Lane-keeping assistance

Highly-accurate lane tracking in tightly constrained locations

Smooth steering response

Reduced driver stress and workload

Rail-like service quality

Automatic vehicle-following control

cooperative adaptive cruise control to reduce driver workload

close-formation vehicle following for increased capacity in high-density locations (an electronically-coupled bus train)

smooth acceleration and deceleration for passenger comfort and reducing energy consumption and emissions


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Last modified: December 27, 2003