DTC Low Carbon TechnologiesFACULTY OF ENGINEERING

Developing a methodology to

quantify emissions associated with

excess capacity in urban transport

systems

Clare Linton, pmcli@leeds.ac.uk

Dr. Susan Grant-Muller

Prof. William Gale

Overview

• Background and context

Defining capacity

The case study area - Greater Manchester

• Approach

Socio-technical system and capacity

• Developing a framework to quantify capacity and emissions

• Future work, Summary and Conclusions

Background Approach Framework Conclusions

Background and context

• Urban transport

dominated by private car

travel and flow is

concentrated into peaks

• Average UK car

occupancy is 1.6

persons

• Collaborative consumption uses resources more

sustainably and could help utilise excess transport

capacity

Data from (Department for Transport, 2012)

Background Approach Framework Conclusions

0

200

400

600

800

1000

1200

1400

1600

1800

Nu

mb

er

of

veh

icle

s

Vehicle Mix A34 Manchester (both directions, weekday)

HGV

LGV

Buses/Coaches

Cars

Motorcylces

Pedal Cycles

Defining Capacity

• This work defines capacity as the space within the transport

system through which transport demand can be met

• This refers to physical space, both within vehicles and the

roadspace, which can facilitate mobility.

• There are also elements of temporal capacity, with periods

of high and low loading

Background Approach Framework Conclusions

Research Questions

1. How much excess capacity is there within the urban

transport system?

2. What is the potential for enhanced use of excess capacity

to deliver emission reductions?

3. How can the principles of collaborative consumption be

applied to examine excess capacity in the urban transport

system?

Background Approach Framework Conclusions

Greater Manchester

• Greater Manchester is the

case study area

Large metropolitan county in

NW England

Covers 1276km2

2.6 million residents

10 local authorities

• The framework is applicable

to other urban areas in the

UK and beyond

Background Approach Framework Conclusions

Approach

• Socio-technical systems

capture the range of

technological and socio-

economic factors involved

in a complex system such

as transport

• This figure shows the

factors involved in urban

transport capacity

Socio-technical configuration for urban transport

capacity (adapted from (Geels, 2002))

Background Approach Framework Conclusions

• This figure shows the

elements that are captured

in the current framework

presented here (those

excluded are in greyed

italics)

• Additional factors are

incorporated in future work

and others are included as

exogenous factors

Socio-technical system and

capacity

Socio-technical configuration for urban transport

capacity (adapted from (Geels, 2002))

Background Approach Framework Conclusions

The framework

• The following section presents the framework for

quantifying excess capacity in urban transport systems and

the potential emission reductions.

• This is done mainly through the presentation of a flow chart

and more detail about the inputs, processes and outputs

Background Approach Framework Conclusions

Flow chart of framework

Flow chart of framework

Inputs to the framework

• Survey

500 residents of Greater Manchester

Questions include information about journeys in last 7 days, mode,

journey purpose, time of day and occupancy rates

Survey conducted by Accent MR

• Fleet Data

Vehicle available space (number of seats / standing room)

Vehicle fuel type

Vehicle size

Emission factors

Background Approach Framework Conclusions

Flow chart of framework

Outputs from the framework

• The main outputs are:

• Fractional vehicle excess capacity (for individual modes

and a mode weighted value)

• CO2 emissions (per person per week)

Background Approach Framework Conclusions

Vehicle Average

Occupancy

Comfort Case Extreme Case

Available

Space

Associated

Excess Capacity

Available

Space

Associated Excess

Capacity

Car (national

average)

1.6 4 60% 5 68%

Car (GM peak) 1.22 4 70% 5 76%

Car (GM off

peak)

1.36 4 66% 5 73%

Local Bus

(national

average)

9.5 70 86% 85 89%

London Bus 19.3 70 74% 85 77%

Examples of vehicle fractional

excess capacity

Background Approach Framework Conclusions

Future work within this project

• Scenario construction for future use of urban transport

capacity in emission reductions

• Traffic network modelling of capacity scenarios

• Additional indicators of capacity

Roadspace capacity

Delays and congestion

Background Approach Framework Conclusions

Conclusions

• Options available for utilising excess capacity include car

sharing and re-allocation of roadspace for public transport

• Given current occupancy rates for cars and buses, between

60-89% of capacity is excess

• It remains to be seen what the rebound effects and impacts

of induced congestion might be

• Achieving an 80% reduction in emissions by 2050 is

challenging, using excess capacity could contribute to this

Background Approach Framework Conclusions

Thanks for your attention

Clare Linton

pmcli@leeds.ac.uk