Post on 16-Dec-2015
transcript
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Network Design
Unit 4: Service Planning & Network Design
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Outline
• Stages of Service Planning• Network Design– Overview– Types of Lines– Network Types
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
STAGES OF SERVICE PLANNING
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Service Planning Steps
Crew scheduling
Vehicle scheduling
Timetabling
Frequency determination
Route design and stop layout
Network design
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Service Planning Steps
Frequency
determination
Timetabling
Vehicle scheduling
Crew scheduling
Route design and stop layout
Network design
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
NETWORK DESIGN OVERVIEW
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Network Design Decisions
• Rare to approach from scratch– Existing route patterns & infrastructure
dictate– New services complement existing services
• New major investment (rail line, etc)– Significant restructuring
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Network Design Decisions
• Geographic coverage• Temporal coverage• Connectivity (direct vs. indirect service)
• Experiment with network structures and routes– Travel demand models– Link major activity centers
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Network Design Objectives
Maximum transportation workMaximum operating efficiencyCreate positive impacts
Passenger Attraction
Network Operating EfficiencyNetwork-City Interactions
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
TYPES OF TRANSIT LINES
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Types of Transit Lines
• Radial• Diametrical• Tangential• Circumferential• Trunk with branches• Trunk with feeder• Loops on lines
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Radial
• One terminus in city center and another outside
• Sharp peaking
• Can be used with branching
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Diametrical (through)
• Connect suburbs on both sides through the city center
• Inbound delays propagate
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Tangential (crosstown)
• Run tangent to city
• Common with grid patterns
• Lower & less peaked demand
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Circumferential
• Ring around city• Suburb-to-suburb
connections without trip into city
• More connections• No terminal time
Moscow
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Trunk lines
Trunk with branches
Trunk with feeders
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Trunk lines
Trunk with branches+ Continuous service with no
transfers+ No transfer stations+ Less terminal time
Trunk with feeders+ Each line optimized+ Higher performance mode
on trunk+ More reliable+ Feeder to feeder transfers
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Frequencies
• One key to quality of service• What do branches mean for frequency?
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Frequencies
• One key to quality of service• What do branches mean for frequency?• One of three things:
1. Branches have less frequent service2. One branch connects into another3. Vehicle separates onto both (rare)
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Loops on Lines
• Closed circle • Usually one-way
operation• Distribution in CBD
Chicago
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Directness
• Most examples so far were rail• Bus routes often deviate to serve lower
densities
• I, U, S, O
Direct
Circuitous
Deviating
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
In-class Exercise
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
TRANSIT NETWORK TYPES
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Transit Network Types
• Radial networks• Radial / circumferential networks• Rectangular or grid networks• Ubiquitous networks
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Radial Networks
+ Maximize ridership along major travel direction
+ Limited transfers
− Extreme concentration in CBD
− Unattractive for crosstowns
− Less coverage area METRA in Chicago
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Radial / Circumferential Networks
• Radial with a ring or tangent
• Greater diversity of origin / destination
• Greater coverage
Koln, Germany
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Grid Networks
• Large area with uniform density
• Coverage• Substantial transfers
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Joy of Grids
• Ability to travel from anywhere to anywhere• Mathematically, the most efficient manner is a
grid• Why?
Rectangular Spiderweb
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Ubiquitous Networks
Coverage over all central area+
Radiating out with branches into suburbs=
perfect network
Most complete ubiquitous network in the world: Paris!! New York is OK too.
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Network Issues
• Radial lines with branches lead to unused capacity at ends
• Different lengths / volume branches make irregular trunks
• Diametrical with different loads• Triangular connections hard to schedule
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Conclusion
• It is rare to approach network design from scratch– Existing route patterns & infrastructure dictate– New services complement existing services
• Network design determines many factors of service quality
Materials developed by K. Watkins, J. LaMondia and C. Brakewood
Reference
Materials in this lecture were taken from:• Walker, J. (2011). Human transit: How clearer
thinking about public transit can enrich our communities and our lives. Island Press.
• Vukan Vuchic, “Urban Transit Operations, Planning and Economics” (2005)
• Mark Hickman, Fundamentals of Transportation wikibook, “Network Design & Frequency”, http://en.wikibooks.org/wiki/Fundamentals_of_Transportation/Network_Design_and_Frequency