PRT System CapacityPRT System CapacityMarch 6, 2009

J. Sam Lott, P.E.Kimley-Horn and Associates, Inc.

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Presentation OverviewPresentation Overview

• Capacity – Defining the Issues

• Station Operations

• Main Line

• Station/Main Line Transition Zone

• Vehicle Occupancy

• Conclusions

• Capacity – Defining the Issues

• Station Operations

• Main Line

• Station/Main Line Transition Zone

• Vehicle Occupancy

• Conclusions

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Capacity – Defining the IssuesCapacity – Defining the Issues

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Capacity – Defining the IssuesCapacity – Defining the Issues

• Safety

• Operational sustainability

• Failure mode recovery/work-around

• Redundant elements: More is not necessarily better

• Public perception may negate some solutions

• Safety

• Operational sustainability

• Failure mode recovery/work-around

• Redundant elements: More is not necessarily better

• Public perception may negate some solutions

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Station OperationsStation Operations

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Station Operational Capacity – A premise for the near term

Station Operational Capacity – A premise for the near term

As important as line capacity issues are,

the successful application of PRT systems

will be determined by the practical and

sustainable operational capacity limits of

the stations serving the peak demand

conditions of the system.Ref. 2006 PT Expo “PRT Stations – System Capacity

Implications” by J. Sam Lott and Jill Capelli

As important as line capacity issues are,

the successful application of PRT systems

will be determined by the practical and

sustainable operational capacity limits of

the stations serving the peak demand

conditions of the system.Ref. 2006 PT Expo “PRT Stations – System Capacity

Implications” by J. Sam Lott and Jill Capelli

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Operational Concept and Station Configuration

Operational Concept and Station Configuration

• Serial Station Berths

– FIFO with head-end loading position(s)

– FIFO with platooning and simultaneous loading positions

• Parallel Station Berths

– Parallel In-Line

– Parallel Only Berths

• Serial Station Berths

– FIFO with head-end loading position(s)

– FIFO with platooning and simultaneous loading positions

• Parallel Station Berths

– Parallel In-Line

– Parallel Only Berths

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Serial Berths - Head End LoadSerial Berths - Head End LoadLoad and Unload Positions

Unload only Positions

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Serial Berths – PlatooningSerial Berths – Platooning

Receiving TrackStaging Positions

Dispatch TrackStaging Positions

Unload/ Load Berths

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Parallel Berths – In LineParallel Berths – In Line

Parallel Berth

Station GuidewayMainline Guideway

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Parallel Berths – With ReversingParallel Berths – With Reversing

Receiving TrackStaging Positions

Dispatch TrackStaging Positions

Unload/ Load Berths

Parallel Berths

Serial Berths

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Conclusions on Station CapacityConclusions on Station Capacity

Dwell time is #1 variable• 2 to 20 sec. in theoretical studies, but passenger

interactions could increase these values

• Communication of loading berth location is complicated for visually impaired passengers

• Extended dwell times required for elderly and handicapped

• Loading and unloading of baggage significantly impacts dwell times

Dwell time is #1 variable• 2 to 20 sec. in theoretical studies, but passenger

interactions could increase these values

• Communication of loading berth location is complicated for visually impaired passengers

• Extended dwell times required for elderly and handicapped

• Loading and unloading of baggage significantly impacts dwell times

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Conclusions on Station CapacityConclusions on Station Capacity

Number of loading berths #2 variable

• Station dimensions are a practical limit

Berth configuration (serial berths versus parallel berths) is #3 variable

• Parallel berths reduce dwell and reliability impacts, but slow down operating speeds

Number of loading berths #2 variable

• Station dimensions are a practical limit

Berth configuration (serial berths versus parallel berths) is #3 variable

• Parallel berths reduce dwell and reliability impacts, but slow down operating speeds

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Conclusions on Station CapacityConclusions on Station Capacity

For the first PRT Systems we will implement (i.e., next ten years), the following are proposed practical maximums for planning purposes:

– Single-sided stations

– 6 to 8 berths

– 500 to 1000 vehicles/hr

– 1000 to 2000 passengers/hr

For the first PRT Systems we will implement (i.e., next ten years), the following are proposed practical maximums for planning purposes:

– Single-sided stations

– 6 to 8 berths

– 500 to 1000 vehicles/hr

– 1000 to 2000 passengers/hr

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Main LineMain Line

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Main Line CapacityMain Line Capacity

Mainline throughput capacity issues include:– Sustainable operating headway– Empty vehicle mix– Average passenger occupancy of loaded

vehicles

Ref. 2005 TRB “Capacity Analysis of Demand Responsive Systems” by J. Sam Lott and

David S. Tai

Mainline throughput capacity issues include:– Sustainable operating headway– Empty vehicle mix– Average passenger occupancy of loaded

vehicles

Ref. 2005 TRB “Capacity Analysis of Demand Responsive Systems” by J. Sam Lott and

David S. Tai

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Operating HeadwayOperating Headway

Determined by:• Synchronous control means that provides

space (or “slot”) for merging vehicles to enter the Main Line flow

• Brick wall stop safety criteria

• Sustainable average spacing between vehicles that accounts for operational perturbations – i.e., the real world

Determined by:• Synchronous control means that provides

space (or “slot”) for merging vehicles to enter the Main Line flow

• Brick wall stop safety criteria

• Sustainable average spacing between vehicles that accounts for operational perturbations – i.e., the real world

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Station/Main Line Transition ZoneStation/Main Line Transition Zone

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Designations of Operating ZonesDesignations of Operating Zones

• Station Guideway – Low speed operations with special train control considerations

• Main Line Guideway – Full speed operations under ATP safety functions

• Station/Main Line Transition Zone – Acceleration/deceleration zones where hand-off occurs between Station and Main Line control functions

• Station Guideway – Low speed operations with special train control considerations

• Main Line Guideway – Full speed operations under ATP safety functions

• Station/Main Line Transition Zone – Acceleration/deceleration zones where hand-off occurs between Station and Main Line control functions

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Vehicle OccupancyVehicle Occupancy

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Vehicle OccupancyVehicle Occupancy

• Determined by the local demographic effect on travel party size (e.g., % of families)

• Shared ride options heavily effected by:– Safety culture and physical context– Trip patterns conducive to shared ride– Surge flow characteristics

• Empty vehicle management and storage locations drive the mix of empty vehicles A new ASCE APM Conference paper by Ingmar Andréasson addresses some of these aspects

• Determined by the local demographic effect on travel party size (e.g., % of families)

• Shared ride options heavily effected by:– Safety culture and physical context– Trip patterns conducive to shared ride– Surge flow characteristics

• Empty vehicle management and storage locations drive the mix of empty vehicles A new ASCE APM Conference paper by Ingmar Andréasson addresses some of these aspects

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ConclusionsConclusions

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Is Capacity a Big Deal? YESIs Capacity a Big Deal? YES

Message to Owners/Developers –

PRT is ready for consideration, however:

• Suitability must be determined for each specific application

• Operations are very complex

• Hidden capacity constraints can exist

• Solutions applying redundant elementsmay penalize PRT effectiveness

Message to Owners/Developers –

PRT is ready for consideration, however:

• Suitability must be determined for each specific application

• Operations are very complex

• Hidden capacity constraints can exist

• Solutions applying redundant elementsmay penalize PRT effectiveness

Kimley-Horn and Associates, Inc.

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Is Capacity a Big Deal? YESIs Capacity a Big Deal? YES

Message to Planners/Suppliers –

PRT is ready for consideration, however:

• Don’t force fit PRT to all applications

• Be patient and let PRT technology mature before assuming capacity capabilities

• Listen to what transit professionals have learned through experience

•

Message to Planners/Suppliers –

PRT is ready for consideration, however:

• Don’t force fit PRT to all applications

• Be patient and let PRT technology mature before assuming capacity capabilities

• Listen to what transit professionals have learned through experience

•

Kimley-Horn and Associates, Inc.

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Is Capacity a Big Deal? YESIs Capacity a Big Deal? YES

Message to Transit Professionals –

PRT is ready for consideration, however:

• Capacity vs. safety issues are critically important to understand

• Consider the world-wide design context

• Be open minded, while remaining protective of passenger safety

Message to Transit Professionals –

PRT is ready for consideration, however:

• Capacity vs. safety issues are critically important to understand

• Consider the world-wide design context

• Be open minded, while remaining protective of passenger safety

CARBON-FREE MOBILITY CONFERENCE

PRT System CapacityPRT System CapacityMarch 6, 2009

J. Sam Lott, P.E.Kimley-Horn and Associates, Inc.