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PRT System CapacityPRT System CapacityMarch 6, 2009
J. Sam Lott, P.E.Kimley-Horn and Associates, Inc.
CARBON-FREE MOBILITY CONFERENCE
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
Serial Berths - Head End LoadSerial Berths - Head End LoadLoad and Unload Positions
Unload only Positions
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
Serial Berths – PlatooningSerial Berths – Platooning
Receiving TrackStaging Positions
Dispatch TrackStaging Positions
Unload/ Load Berths
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
Parallel Berths – In LineParallel Berths – In Line
Parallel Berth
Station GuidewayMainline Guideway
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
Parallel Berths – With ReversingParallel Berths – With Reversing
Receiving TrackStaging Positions
Dispatch TrackStaging Positions
Unload/ Load Berths
Parallel Berths
Serial Berths
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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
Kimley-Horn and Associates, Inc.
CARBON-FREE
MOBILITY CONFERENCE
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.
CARBON-FREE
MOBILITY CONFERENCE
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.
CARBON-FREE
MOBILITY CONFERENCE
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