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.
Highlights
Urban sprawl is observed in many countries around the world after decades of road dominated infrastructure investment
Fu et al (2014) applied a reliabilitybased user equilibrium (RUE) approach in a multi-modal network to determine the mode and route choice, assuming that all users have a common objective of minimising a routeutility function based on travel time budget (TTB) (Lo et al 2006)
We proposed a new multi-objective spatial analysis framework to evaluate the economic, environmental and health impacts of urban development and transport investment strategies in a linear monocentric city with continuum demand distribution, where residents have access to a road at any location or rail services by walking or cycling to the nearest station
Summary
Urban sprawl is observed in many countries around the world after decades of road dominated infrastructure investment. In particular, we model decisions with multiple objectives at two levels: (1) urban growth, transport planning, air quality and health impact assessment at the policy decision level; and (2) behavioural response at the user level in terms of mode and route choice. We introduce a multi-objective equilibrium model at the lower level for a bi-modal network in order to determine more realistically where modal shifts might occur and where active modes are used With this formulation at the lower level, multiple system performance indicators can be observed at the upper level for different (pre-defined) urban growth and transport investment scenarios. The lower level model enables a health impact assessment (at the upper level) that takes into the spatially disaggregate emissions concentrations encountered by travellers, and mode-specific uptake of pollutants.
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