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

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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

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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

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TYPES OF TRANSIT LINES

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Types of Transit Lines

• Radial• Diametrical• Tangential• Circumferential• Trunk with branches• Trunk with feeder• Loops on lines

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Radial

• One terminus in city center and another outside

• Sharp peaking

• Can be used with branching

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Diametrical (through)

• Connect suburbs on both sides through the city center

• Inbound delays propagate

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Tangential (crosstown)

• Run tangent to city

• Common with grid patterns

• Lower & less peaked demand

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Circumferential

• Ring around city• Suburb-to-suburb

connections without trip into city

• More connections• No terminal time

Moscow

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Trunk lines

Trunk with branches

Trunk with feeders

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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?

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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)

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Loops on Lines

• Closed circle • Usually one-way

operation• Distribution in CBD

Chicago

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Directness

• Most examples so far were rail• Bus routes often deviate to serve lower

densities

• I, U, S, O

Direct

Circuitous

Deviating

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In-class Exercise

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TRANSIT NETWORK TYPES

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Transit Network Types

• Radial networks• Radial / circumferential networks• Rectangular or grid networks• Ubiquitous networks

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Radial Networks

+ Maximize ridership along major travel direction

+ Limited transfers

− Extreme concentration in CBD

− Unattractive for crosstowns

− Less coverage area METRA in Chicago

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Radial / Circumferential Networks

• Radial with a ring or tangent

• Greater diversity of origin / destination

• Greater coverage

Koln, Germany

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Grid Networks

• Large area with uniform density

• Coverage• Substantial transfers

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Joy of Grids

• Ability to travel from anywhere to anywhere• Mathematically, the most efficient manner is a

grid• Why?

Rectangular Spiderweb

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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.

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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

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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

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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