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

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.