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

Air Pollution Exposure in Relation to the Commute to School: A Bradford UK Case Study

Walking School Buses (WSBs) provide a safe alternative to being driven to school. Children benefit from the contribution the exercise provides towards their daily exercise target, it gives children practical experience with respect to road safety and it helps to relieve traffic congestion around the entrance to their school. Walking routes are designed largely based in road safety considerations, catchment need and the availability of parent support. However, little attention is given to the air pollution exposure experienced by children during their journey to school, despite the commuting microenvironment being an important contributor to a child’s daily air pollution exposure. This study aims to quantify the air pollution exposure experienced by children walking to school and those being driven by car. A school was chosen in Bradford, UK. Three adult participants carried out the journey to and from school, each carrying a P-Trak ultrafine particle (UFP) count monitor. One participant travelled the journey to school by car while the other two walked, each on opposite sides of the road for the majority of the journey. Data collection was carried out over a period of two weeks, for a total of five journeys to school in the morning and five on the way home at the end of the school day. Results of the study suggest that car commuters experience lower levels of air pollution dose due to lower exposure and reduced commute times. The largest reductions in exposure for pedestrians can be achieved by avoiding close proximity to traffic queuing up at intersections, and, where possible, walking on the side of the road opposite the traffic, especially during the morning commuting period. Major intersections should also be avoided as they were associated with peak exposures. Steps to ensure that the phasing of lights is optimised to minimise pedestrian waiting time would also help reduce exposure. If possible, busy roads should be avoided altogether. By the careful design of WSB routes, taking into account air pollution, children will be able to experience the benefits that walking to school brings while minimizing their air pollution exposure during their commute to and from school

Bi-objective network equilibrium, traffic assignment and road pricing

Multi-objective equilibrium models of traffic assignment state that users of road networks travel on routes that are efficient with respect to several objectives, such as travel time and toll. This concept provides a general framework for modelling traffic flow in tolled road networks. We present the concept of time surplus maximisation as a way of handling user preferences. Given a toll, users have a maximum time they are willing to spend for a trip. Time surplus is this maximum time minus actual travel time. A rational user can be assumed to maximise time surplus, leading to the definition of time surplus maximisation bi-objective user equilibrium. We propose to use such models on the lower level of bi-level models for pricing in road networks under multiple upper level objectives such as minimising total travel time and emissions. In such a model a multi-objective optimisation problem at the upper level is combined with a multi-objective equilibrium problem at the lower level

Exploring Parental Perceptions about School Travel and Walking School Buses: A Thematic Analysis Approach

Establishing a less car-oriented mobility ethos through initiatives targeting, among others, children’s travel to school could be a key for unlocking the potential for a more sustainable future. A Walking School Bus (WSB) is a relatively new and scarcely evaluated commuting mechanism that in theory provides a creative scheme capable of inspiring voluntary travel behaviour change for children and parents. Through a series of in-depth focus group sessions that were conducted in Bradford, UK this article explores the perceptions of parents that are ultimately the decision-makers about how their children go to school. This work improves the understanding of the different challenges and opportunities underpinning travel to school, in general, and WSBs, in particular, by identifying and discussing six thematic areas of critical importance that explain the decision-making behind potential WSB uptake. These are namely: logistics, safety, trust, health and wellbeing, emotional needs and educational opportunities. Finally, the paper provides policy recommendations about how WSB initiatives can become more effective and attractive mobility tools for local communities

Understanding factors influencing choices of cyclists and potential cyclists: A case study at the University of Auckland

Like many other cities in the world, Auckland has been very much a car-based city for decades, with a car modal share of almost 80%. Promoting the use of active modes, including walking and cycling, is no doubt one of the key strategies that should be considered in transport planning. To help transform Auckland into a bicycle-friendly city, our first step is to determine the motivators and deterrents to cycling. This study has two components. We first performed a comprehensive literature review of the lessons learnt from international experience, focussing on what factors were found to have significant influence on the decision to use bicycles as a mode of transport. Based on the findings, we designed a web-based survey to identify the factors influencing the decision to commute by bicycle or not, as well as cyclists’ and potential cyclists’ route choice criteria. A pilot survey was conducted at the University of Auckland as a case study and the survey results were consistent with our findings from the literature review. We conclude that there are five main factors missing in Auckland in terms of encouraging cycling, namely: (1) safety; (2) a well-connected network of cycleways; (3) convenience; (4) policies to discourage car use; and (5) a good public transportation system integrated with cycling facilities

Mutations underlying 3-Hydroxy-3-Methylglutaryl CoA Lyase deficiency in the Saudi population

BACKGROUND: 3-Hydroxy-3-Methylglutaric aciduria (3HMG, McKusick: 246450) is an autosomal recessive branched chain organic aciduria caused by deficiency of the enzyme 3-Hydroxy-3-Methylglutaryl CoA lyase (HL, HMGCL, EC 4.1.3.4). HL is encoded by HMGCL gene and many mutations have been reported. 3HMG is commonly observed in Saudi Arabia. METHODS: We utilized Whole Genome Amplification (WGA), PCR and direct sequencing to identify mutations underlying 3HMG in the Saudi population. Two patients from two unrelated families and thirty-four 3HMG positive dried blood spots (DBS) were included. RESULTS: We detected the common missense mutation R41Q in 89% of the tested alleles (64 alleles). 2 alleles carried the frame shift mutation F305fs (-2) and the last two alleles had a novel splice site donor IVS6+1G>A mutation which was confirmed by its absence in more than 100 chromosomes from the normal population. All mutations were present in a homozygous state, reflecting extensive consanguinity. The high frequency of R41Q is consistent with a founder effect. Together the three mutations described account for >94% of the pathogenic mutations underlying 3HMG in Saudi Arabia. CONCLUSION: Our study provides the most extensive genotype analysis on 3HMG patients from Saudi Arabia. Our findings have direct implications on rapid molecular diagnosis, prenatal and pre-implantation diagnosis and population based prevention programs directed towards 3HMG

Adducts of DNA and Anthracycline Antibiotics: Structure, Function and Activities

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Modelling route choice behaviour in a tolled road network with a time surplus maximisation bi-objective user equilibrium model

In this paper, we propose a novel approach to model route choice behaviour in a tolled road network with a bi-objective approach, assuming that all users have two objectives: (1) minimise travel time; and (2) minimise toll cost. We assume further that users have different preferences in the sense that for any given path with a specific toll, there is a limit on the time that an individual would be willing to spend. Different users can have different preferences represented by this indifference curve between toll and time. Time surplus is defined as the maximum time minus the actual time. Given a set of paths, the one with the highest (or least negative) time surplus will be the preferred path for the individual. This will result in a bi-objective equilibrium solution satisfying the time surplus maximisation bi-objective user equilibrium (TSmaxBUE) condition. That is, for each O-D pair, all individuals are travelling on the path with the highest time surplus value among all the efficient paths between this O-D pair. We show that the TSmaxBUE condition is a proper generalisation of user equilibrium with generalised cost function, and that it is equivalent to bi-objective user equilibrium. We also present a multi-user class version of the TSmaxBUE condition and demonstrate our concepts with illustrative examples

Travel time minimization versus reserve capacity maximization in the network design problem

In the classical continuous network design problem, the most common approach is to determine optimal capacity enhancement by minimizing the total system cost under a budget constraint while taking into account the route choice behavior of network users. An alternative objective, maximization of network reserve capacity, is examined with the expectation that it is equivalent to total system cost minimization to a certain extent. The two approaches are tested and the results are compared in order to assess the level of equivalence and their effectiveness. The level of equivalence of the two objectives is found to vary by level of congestion. When the level of congestion is low, maximization of network reserve capacity is found to have the simultaneous effect of total cost minimization. This objective becomes more desirable when the level of congestion is low. When the level of congestion is high, maximizing the reserve capacity can only. minimize the total travel cost to a certain extent. In this case, a combined objective can also be considered by applying different weightings on the two objectives

Locating and pricing park-and-ride facilities in a linear monocentric city with deterministic mode choice

This paper investigates the optimal location and pricing of a park-and-ride (P&R) facility in a linear city. Residences are uniformly distributed from the center to the exogenous city boundary, and all trips are from home to the center. A congestible highway and a congestion-free railway can be accessed at all points along the travel corridor. Deterministic mode choice equilibria are characterized for before and after a P,&R service is introduced. Profit maximizing and social cost minimizing P&R locations and parking charges are then derived and compared. A numerical example illustrates the possibility of a "win-win" situation whereby a P&R facility can be profitable, as well as socially beneficial by reducing total travel costs. (C) 2004 Elsevier Ltd. All rights reserved