The Value of Travel Time Savings and the Link with Income: Implications for Public Project Evaluation

This paper summarises the link between the value of travel time savings (VTTS) and income levels found in various empirical studies. Most studies find that VTTS increases with income but less than proportionately. A square root relationship with household income relative to mean incomes is suggested as a useful approximation, although no theoretical support is offered. Actual project evaluations generally ignore changes in VTTS with income, i.e., government agencies follow an equity principle and value time the same for all users. But this results in an asymmetric treatment of benefits and costs. Benefit-cost studies normally do not make an income adjustment for monetary benefits and costs, but ignoring the link between incomes and VTTS means agencies do implicitly make an income adjustment for time savings. This could distort project ranking depending on the relative importance of time versus monetary benefits and costs, and/or the mix of income- and timeconstrained travellers affected by the project

Variations in the Value of Travel Time Savings: Empirical Studies and the Values for Road Project Evaluation

This paper focuses on the variations in values of travel time savings (VTTS) found in different empirical studies and used for road project evaluation in a number of countries and jurisdictions. Estimates of VTTS, expressed as a percentage of the wage, from 56 empirical studies show a substantial range, over a ten-fold variation. The estimates cluster between about 30 to 50 percent of the wage, but this is still sizeable variation across studies. The VTTS used for road project evaluations are compiled from a number of agencies and countries, and expressed in a common currency. The range of values is substantial, not just across countries but across agencies within a country. Because of the importance of time savings in transport project evaluation, this implies considerable inconsistency in the application of economic analysis to road project evaluation in different jurisdictions. There is a need not only for more research on VTTS but more communication about the figures being used in project evaluation frameworks

A survey of recent estimates of price elasticities of demand for transport

This paper reviews 70 estimates of the price elasticity of demand for many different transport modes and market situations. The paper presents figures separately for passenger and freight transport and include estimates of both own-price and mode choice elasticities. It also presents some elasticity estimates on demand for gasoline, together with selected cross-price elasticities. In addition, it includes a brief exposition on the different concepts of elasticity - compensated, uncompensated, price, cross-price and mode choice - and discusses the relations between them. This paper shows that, since transportation is a derived demand, it tends to be inelastic. Although the review is confined to estimates of price elasticities, it notes that quality variables are often more important than price, particularly in the air, motor freight, and container markets. Finally, most of the estimates relate to developed countries, reflecting the availabilty of data, research resources, and domicile of the researchers. The elasticity estimates are nevertheless thought to be relevant to developing countries as well. But since intermodal competition is generally less intense in developing countries, this tends to make transport demand more inelastic, although the lower income levels in such countries may partly offset this effect.Environmental Economics&Policies,Economic Theory&Research,Access to Markets,Markets and Market Access,Consumption

An Overview of PIMMS (A Pricing and Investment Model for Multi-Modal Systems): An Areawide Urban Transport Policy Evaluation Model

The resurgence of interest in building better cities provides an opportunity to develop improved land use-transport models; models which are responsive to a wide variety of planning options, in contrast to current urban transport models which are only suitable for evaluating a limited number of major infrastructure options. A wide set of policy tools includes new infrastructure such as private tolled roads, light rail, bus priority systems; travel demand management through road pricing, area licensing and banning of cars in particular locations; and land use incentives/disincentives such as zoning for higher density activity, and more stringent environmental standards. To be responsive to a wide range of policy choices, it is desirable to develop models with a strong foundation in individual behaviour. This paper presents an overview of a project funded by the Australian Research Council. The aim is to develop a computer-based forecasting tool to give planners more flexibility in evaluating strategies designed to improve the performance of cities

Effects of rare kidney diseases on kidney failure: a longitudinal analysis of the UK National Registry of Rare Kidney Diseases (RaDaR) cohort

Background Individuals with rare kidney diseases account for 5–10% of people with chronic kidney disease, but constitute more than 25% of patients receiving kidney replacement therapy. The National Registry of Rare Kidney Diseases (RaDaR) gathers longitudinal data from patients with these conditions, which we used to study disease progression and outcomes of death and kidney failure. Methods People aged 0–96 years living with 28 types of rare kidney diseases were recruited from 108 UK renal care facilities. The primary outcomes were cumulative incidence of mortality and kidney failure in individuals with rare kidney diseases, which were calculated and compared with that of unselected patients with chronic kidney disease. Cumulative incidence and Kaplan–Meier survival estimates were calculated for the following outcomes: median age at kidney failure; median age at death; time from start of dialysis to death; and time from diagnosis to estimated glomerular filtration rate (eGFR) thresholds, allowing calculation of time from last eGFR of 75 mL/min per 1·73 m2 or more to first eGFR of less than 30 mL/min per 1·73 m2 (the therapeutic trial window). Findings Between Jan 18, 2010, and July 25, 2022, 27 285 participants were recruited to RaDaR. Median follow-up time from diagnosis was 9·6 years (IQR 5·9–16·7). RaDaR participants had significantly higher 5-year cumulative incidence of kidney failure than 2·81 million UK patients with all-cause chronic kidney disease (28% vs 1%; p<0·0001), but better survival rates (standardised mortality ratio 0·42 [95% CI 0·32–0·52]; p<0·0001). Median age at kidney failure, median age at death, time from start of dialysis to death, time from diagnosis to eGFR thresholds, and therapeutic trial window all varied substantially between rare diseases. Interpretation Patients with rare kidney diseases differ from the general population of individuals with chronic kidney disease: they have higher 5-year rates of kidney failure but higher survival than other patients with chronic kidney disease stages 3–5, and so are over-represented in the cohort of patients requiring kidney replacement therapy. Addressing unmet therapeutic need for patients with rare kidney diseases could have a large beneficial effect on long-term kidney replacement therapy demand. Funding RaDaR is funded by the Medical Research Council, Kidney Research UK, Kidney Care UK, and the Polycystic Kidney Disease Charity

Monitoring the Performance of Government Trading Enterprises

To assess in quantitative terms the “resilience” of systems, it is necessary to ask first what is meant by “resilience”, whether it is a single attribute or several, which measure or measures appropriately characterise it. This chapter covers: the technical meanings that the word “resilience” has assumed, and its role in the debates about how best to achieve reliability, safety, etc.; the different possible measures for the attributes that the word designates, with their different pros and cons in terms of ease of empirical assessment and suitability for supporting prediction and decision making; the similarity between these concepts, measures and attached problems in various fields of engineering, and how lessons can be propagated between them