Business Logistics 420Public Transportation

Lecture 20: Transit System Design

Lecture Objectives

• To understand the basic elements of transit system design

• To appreciate the different transit system route configurations

• To know the basic principles of good route design

• To understand other aspects of system design such as schedules, stop location

Elements of Transit System Design

• Overall system -- route interrelationship• Individual route design• Scheduling• Stop locations• Vehicle Selection

System Considerations• Service area definition• Location of major generators• Route pattern -- network

– Radial -- circumferential– Grid -- rectangular– Combination– Irregular

• Route spacing• Transfers -- inter and intra modal• Marketing considerations

Chicago Loop -- Grid Network

Washington Metro -- Radial

CATA -- Radial System

ATA -- Bradford, Pa -- Irregular

Route Design Guidelines

• Use direct routing where possible• Through routing is preferred to cycle

routing• Reverse or loop routing should be used

sparingly• Routes should begin and end at major

generators

Route Design Guidelines (Continued)

• Routes should be spaced about 1/2 mile apart

• Routes should provide direct service -- circuity ratio (actual route miles/direct auto travel) should not exceed 1.33

• Initial route design assumes average speed of 12 miles per hour

CATA - P Route -- Through Routing

CATA C Route -- Poor Circuity

CATA -- CS Route --Reverse or Loop Routing

Factors Influencing Route Design

• Demand– spatial arrangement– special generators

• Urban environment– street network (one-way streets)– congestion

• Management Considerations– driver scheduling– labor rules

Factors Influencing Route Design (Continued)

• Intermodal Coordination– Rail/bus/paratransit– Intercity facilities (rail, bus, air)

• Political Considerations– Equity– Pressure

Scheduling Considerations

• Two major issues– Headway – time between vehicles Ex: 15 minute

headway represents four buses per hour– Timing of arrivals at points along the route

• Factors to consider– quality of service (frequency) – transfers– easy memorization– driver labor requirements

Scheduling Considerations (Continued)

• Setting headways– Maximum headway (fewest minutes between

vehicles) set based on capacity needed to meet demand

– Minimum headway based on policy decisions, e.g., all routes should have no less frequent service than 30 minutes in the peak and 60 minutes off peak

Scheduling Considerations (Continued)

• Setting arrival times– Independent scheduling

• Most common approach• OK if short headways, but may cause transfer problems if long

headways

– Pulse scheduling – timed transfers• Attractive approach for systems with long headways• Improves service quality• Hard to implement due to space constraints at stops and

variability of travel times

Stop Locations• Operations

– location (Near side, far side, mid block)– peak number of buses at stop at any given time

• Quality of service– near destinations– spaced 750 ft or more apart to maintain operating

speed– adequate waiting area -- shelter

Stop Locations (Continued)• The urban environment

– parking restrictions– turns

• Special concerns in “Edge City,” “big box” environment– bus stop near store entrances rather than across

sea of parking– circuity concerns if store too far from road

Vehicle Selection

• Size of vehicle– Peak loads (goal to provide 5 sq ft/psgr so 8 x

40 ft bus = 320 sq ft or 64 passengers max.– Traffic conditions

• street width• turning radius

• Number of vehicles– Peak hour requirement plus 10% spares

Miscellaneous System Design Issues

• Special service types– “freeway flyers”– skip stop operation– local vs express

• New service types– service routes (fixed-route with deviations)– paratransit feeder services

Study Questions• What are the major aspects of transit system

design?• What are the basic types of transit route

network configurations?• What are the basic route design guidelines?• What are “good” route designs? What are

“poor” designs?• What factors influence scheduling decisions?

Study Questions (Continued)

• What factors are important when selecting vehicle size and numbers?

• Pick up a CATA Ride Guide in the HUB, Kern, or inside the doors to Willard (“new” building side on Pollock Rd.) to serve as reference for this lecture