Urban Growth, Transport Planning, Air Quality and Health: A Multi-Objective Spatial Analysis Framework for a Linear Monocentric City

Abstract

In this paper, we propose a multi-objective spatial analysis framework to evaluate the economic, environmental and health impacts of transport investment strategies under different urban growth scenarios. We consider a linear monocentric city (LMC) wherein residents are distributed continuously along an urban corridor and commute daily to a common destination, the central business district (CBD), represented by one end of the linear city. Two modes are available: car and rail. Users can travel from their residence to the CBD by car on a congestible highway with stochastic travel time, or by rail from the most convenient nearby station, which they reach by walking or cycling. Travellers throughout the city have a distribution of reliability preferences. Individual mode choice is determined using the notion of travel time budget surplus to take into consideration the travel time, travel time reliability and monetary cost associated with each mode. We assume users would like to minimise travel time, monetary cost, and maximise travel time reliability. The resulting formulation is a three-objective user equilibrium model (TBSmaxTUE). For the continuous monocentric city model, TBSmaxTUE can be formulated as a fixed point problem. To admit a numerical solution the continuum is discretised, allowing it to be expressed as a standard network equilibrium assignment problem. The performance of this LMC model can then be analysed against multiple objectives. We consider the economic objective to minimise total system travel time; the environmental objective to minimise total tailpipe emissions from car trips; and health objectives to minimise pollutant uptake while also maximising the level of physical activity during the journey to work.

A two-stage residential location and transport mode choice model with exposure to traffic-induced air pollution

“…Question 1 has been addressed by (Schindler et al, 2017;Schindler and Caruso, 2021), while Question 2 has been partially addressed by Wang and Connors (2018). In this paper, we are addressing Questions 1 and 2 together, and making the first step for Questions 3 and 4.…”

“…Transport choices are not modelled but treated as visions. As pointed out in Wang and Connors (2018), a key assumption in ITHIM is that the reduction in road transport trips, as a result of increases in walking and cycling instead of car use, led to equal proportional reduction in pollutants attributed to transport. This assumption might not be realistic; it oversimplifies the relationship between traffic congestion and the resulting air pollution.…”

“…In general, health impact assessment models are not linked to travel behavioural models. Wang and Connors (2018) also emphasised the importance of modelling the localised effect of traffic on air quality and its subsequent effect on the vicinity for the residents as well as the pollutant dose during their journeys to work, depending on their mode choice. Wang and Connors (2018) are the first to model pollutant dose in this context.…”

“…Our model must capture the feedback in the decision making process between the longer-term residential location choice and day-to-day transport choices. In order to do so, we propose a two-stage game theoretical approach to model this process in a bi-modal linear monocentric city (LMC) as in Wang and Connors (2018) depicted in Fig. 1, where residents are distributed continuously along the city.…”

“…An urban equilibrium is reached when no one can improve the utility of their residential location choice by unilaterally moving to another location given the choices of all other residents. Wang and Connors (2018) propose a multi-objective approach to model the transport equilibrium, i.e. a bi-modal three-objective user equilibrium (TUE) model, based on the simultaneous consideration of three objectives: (1) minimise travel time; (2) maximise travel time reliability; and (3) minimise monetary cost.…”