Mark Wardman

A REVIEW OF BRITISH EVIDENCE ON TIME AND SERVICE QUALITY VALUATIONS

A large amount of evidence has been amassed in Great Britain on the values of time and a wide range of service quality attributes. This paper reports meta-analysis of a large number of valuations of these attributes, including in-vehicle time, walk time, wait time, service headway, interchange, departure time adjustments, search time, late time and time spent in congested traffic conditions. This analysis yields insights into methodological issues, supports the appraisal of widely used conventions, can be used to provide estimated valuations for situations where none exist, and allows the assessment of particular findings against a large body of empirical evidence. The research findings challenge several conventions and provide a number of practical recommendations regarding the valuations of time and service quality to use in appraisal and areas for future research.

DRIVER RESPONSE TO VARIABLE MESSAGE SIGNS: A STATED PREFERENCE INVESTIGATION

Abstract This paper uses a Stated Preference approach to undertake a detailed assessment of the effect on drivers’ route choice of information provided by variable message signs (VMS). Although drivers’ response to VMS information will vary according to the availability of alternative routes and the extent to which they are close substitutes, our findings show that route choice can be strongly influenced by the provision of information about traffic conditions ahead. This has important implications for the use of VMS systems as part of comprehensive traffic management and control systems. The principal findings are that the impact of VMS information depends on: the content of the message, such as the cause of delay and its extent; local circumstances, such as relative journey times in normal conditions; and drivers’ characteristics, such as their age, sex and previous network knowledge. The impact of qualitative indicators, visible queues and delays were examined. It was found that not only is delay time more highly valued than normal travel time, which is to be expected, but that drivers become more sensitive to delay time as delay times increased across the range presented.

Twenty Years of Rail Crowding Valuation Studies: Evidence and Lessons from British Experience

Abstract This paper reviews evidence from British experience of the valuation of rail crowding obtained over 20 years from 17 studies. It summarizes these studies, places some useful empirical evidence in the public domain and draws lessons from this considerable body of evidence and experience. Crowding valuations, both for standing and seated in crowding conditions, are summarized in terms of time multipliers, which are inherently more transferable than monetary equivalents. A meta‐analysis of 208 valuations is reported, finding the valuations to vary with load factor and journey purpose. The seating multiplier averages 1.19 and the standing multiplier averages 2.32. The latter is in line with widely used multipliers applied to walking and waiting time. The most recent evidence is based around the number of standing passengers per square metre, thereby providing a more accurate measure of the discomfort of standing since, unlike load factor, it allows for the layout of the carriage and ease with which crowding can be accommodated. As far as methodology is concerned, the paper covers issues such as presenting crowding in ‘stated preference’ exercises and the realism of the crowding levels offered, non‐linearities in the relationship between crowding multipliers and the severity and amount of crowding time, and probabilistic versus deterministic representations of crowding. The paper also identifies future areas for research.

Evaluating the demand for new cycle facilities

There are many studies which report attitudes to cycling and factors affecting the propensity to cycle but very few which evaluate the detailed costs and benefits of new cycle facilities. As part of a review of cycle facility provision in Bradford, West Yorkshire, a large scale survey of current and potential cyclists was conducted in 1994. A stated preference survey design was used to estimate the value placed on the different attributes of four alternative cycle routes under consideration. The results found that safety is more highly valued than time and that some new cycle schemes can be economically justified on the basis of benefits to current cyclists, even in circumstances of relatively low cycle use. The findings are important in the context of the current promotion of cycle facilities and highlights the need for further research and monitoring.

Traffic related noise and air quality valuations: evidence from stated preference residential choice models

This paper reports on research which has estimated valuations of changes in traffic related noise levels and air quality and which contributes to the body of knowledge and to methodology in this area. There are several novel aspects of this research. Firstly, there have been relatively few stated preference studies of the monetary valuations of traffic related noise and air quality. A feature of this analysis is the examination of variations in values according to the size and sign of the environmental change, the currently experienced level of the attribute and various socio-economic factors. Secondly, the important issue of presentation is addressed, with two different methods used in the valuation of air quality and links made between valuations and physical measures. Thirdly, the results from stated preference and the contingent valuation method are compared. Finally, we bring together evidence from other studies and compare them with the findings obtained here.

The UK national cycling strategy: can improved facilities meet the targets?

The Department of Transports recently launched National Cycling Strategy has the aim of doubling the number of cycle trips by 2002 with a further doubling by 2012. The Royal Commission on Environmental Pollution recommended a quadrupling of cycle trips to 10% of all journeys by 2005. Given the increased level of interest in cycling and the role it could play in alleviating congestion and environmental problems, it is important that there are mode choice models which can evaluate the impact and benefits of investment in cycle schemes. The contribution of the research reported here is in the development of an enhanced mode choice model which examines cycling in a greater level of detail than is typically the case. The Stated Preference model provides values of the benefits of unsegregated cycle lanes and segregated cycle paths. Although investment in such facilities could lead to significant increases in cycle demand, such that even costly investments may be worthwhile in economic terms, our results indicate that they could not on their own achieve target levels of increased cycle use. Unsegregated facilities could not even satisfy the Department of Transports medium term objective whilst only in the most favourable set of circumstances could segregated facilities achieve the longer term objective, in the commuting market, of a quadrupling of cycle share. Our results indicate, as might be widely expected, that other traffic management and restraint measures are needed in order to achieve target levels of increased cycle use.

Modelling Tenants' Choices in the Public Rented Sector: A Stated Preference Approach

This paper uses a stated preference (SP) approach to examine the potential housing choices of tenants in the UK public housing sector. The paper begins by explaining the policy significance of the choices that such tenants might make if alternative dwellings were offered to them. It then discusses the SP approach in general before explaining the way in which it is used in this study. The results of the SP modelling exercise are presented. These suggest that tenants are unlikely to move to housing estates that they see as being worse than their current estate solely in response to lower rents. This is because a number of factors other than rent are of more significance in their potential housing decisions.

Inter-urban rail demand, elasticities and competition in Great Britain: Evidence from direct demand models

The aim of this research was to extend direct demand models to analyse elasticity variation in more detail, and in particular to examine the interaction between rail and competing modes. Relatively little is known about the interaction between modes in the inter-urban travel market. We have obtained plausible, precise and reliable estimates of elasticity variation with regard to both the level a variable takes and with respect to the degree of competition from car and coach. These relationships have been freely estimated rather than imposed and would in many instances imply appreciable differences in demand forecasts in comparison with models which do not include competitive effects. As a result of this research, British Rail has amended its forecasting procedures to include competitive effects. We recommend the more widespread use of direct demand models to examine elasticity variation.

STATED PREFERENCE METHODS AND TRAVEL DEMAND FORECASTING: AN EXAMINATION OF THE SCALE FACTOR PROBLEM

Abstract Stated Preference choice models may have incorrect scale properties, because their coefficients incorporate the influence of factors which do not affect actual behaviour, and this paper examines the consequences of this scale factor problem for demand forecasting. Empirical evidence is presented which suggests that the scale factor problem is not serious and the results are generalised to consider the consequences of the scale factor problem in situations other than those prevailing in the empirical example. The paper also examines the predictive performance of three procedures for forecasting changes to an existing demand in the light of the scale factor problem. This indicates that reliance should not be placed on the incremental logit model and that a simple procedure which amends a standard logit model forecast in the light of its performance in explaining the observed initial demand is generally preferred to unadjusted logit model forecasts.

Rail network accessibility and the demand for inter-urban rail travel

This paper reviews methods that have and can be used to forecast the effect of changes in accessibility to the rail network on the demand for inter-urban rail travel and of available evidence on rail accessibility elasticities. It reveals that relatively little research has been conducted in this area and that the forecasting procedures that could be used imply large variation in accessibility elasticities, which has not been empirically justified. Fresh empirical evidence on two related matters is reported. First, the neglected area of choice set composition is examined and the extent to which rail is considered to be a realistic alternative for inter-urban journeys and the contribution that accessibility to the rail network makes to this are analysed. Second, rail trip rate models are presented that not only contain estimates of accessibility elasticities and of the effects of a range of socio-economic variables on the demand for rail travel, but also that allow tests of the accessibility elasticity variation implied by many forecasting procedures to be conducted. It is found that this elasticity variation is not empirically supported. It is concluded that there is only limited scope for increasing rail demand through improvements in rail network accessibility.