Sergio R. Jara-Díaz

The value of travel time savings in evaluation

Values of travel time enter the appraisal scheme both as values for modelling and forecasting and as values for use within project evaluation. This paper considers whether and how travel time values should be used within evaluation. The basic theories of private and social travel time valuation are set out. Issues such as the valuation of working time savings, the case for segmenting values by journey purpose and length, sign and size of time savings and mode of travel, and the income elasticity of the value of time, are reviewed. Two of the main conclusions are that time is a scarce resource and should be valued but that direct use of willingness to pay values is inappropriate for social appraisal of projects. Some form of social weighting scheme is required.

Detection of income effect in mode choice: Theory and application

Although income effect is likely to be present in mode choice for most of the population within the developing world, presently used approaches do not take it into account. In fact, the income variable that sometimes enters utility specifications has been justified as a proxy for other variables, which makes its role rather ambiguous. In this paper, the problem is restated from its microeconomic foundations, showing that the usual non-income-sensitive specifications can be interpreted as a particular case within a more general framework which provides the basis for a methodology to test the presence of income effect. The methodology, which does not require additional information besides the usual data collected for disaggregate models, is applied to trips to work originated in a middle-income corridor of Santiago, Chile. The results quantitatively confirm previous qualitative analysis, and show empirically the need to employ income-sensitive mode choice models.

VALUE OF TIME SENSITIVITY TO MODEL SPECIFICATION

We compare values of time obtained with linear utility functions used in LOGIT and HIERARCHICAL LOGIT specifications of a nine-mode passenger choice model estimated with disaggregate data from Santiago, Chile, and find that they are sensitive to the specification used, unconvincingly high, and imply that the value of waiting time is a decreasing function of income. We then find that removing observations for individuals who face limiting values of price or service level yields partially improved results if the utility functions are still linear; but the most convincing results are obtained with explicitly nonlinear BOX-COX LOGIT specifications.

On the goods-activities technical relations in the time allocation theory

In areas like household production and travel choice, time assigned to the different activities plays a key role in addition to consumption as the main variables in utility within the consumer behaviour framework. However, a comprehensive conceptual structure to understand the technological relations between goods consumption and the assignment of time to activities is still lacking. In this paper the problem is reviewed and all possible relations between goods and time are re-formulated. Two general functions are defined and proposed to account for all these relations, forming a new taxonomy for the technical constraints. The resulting consumer behaviour model is used to obtain general expressions for both the value of saving time in constrained activities like travel, and the value of leisure.

Optimal pricing for priority service and space allocation in container ports

This paper focuses on the determination of optimal space allocation and optimal pricing for priority systems in container ports. The problem is formulated taking into account the intrinsic and logistic cargo value, and a capacity constraint that considers the various physical requirements of the containers. Prices and space allocations are found for various cases, showing explicitly the role of each element. The resulting models extend classical price differentiation theory, i.e. the inverse elasticity rule, in various directions. Finally, the implications of these results and the corresponding information requirements are clearly established.

A multioutput cost function for the services of Spanish ports' infrastructure

A long run multioutput cost function for the infrastructure services of Spanish ports is estimated using 286 observations on 26 ports during 11 years. Cargo specific marginal costs and the degree of economies of scale and scope are calculated up to a port level. Results show that liquid bulk and non-containerised general cargo present the lowest and largest marginal cost, respectively. Increasing returns to scale are present in general and for each and every port. A scope analysis indicates that port specialisation is not appropriate from the viewpoint of infrastructure.

Adapting Productivity Theory to the Quadratic Cost Function. An Application to the Spanish Electric Sector

In this article we have adapted productivity analysis to the case of a cost model using a quadratic cost function and discrete data. The main theoretical result is a productivity index that can be decomposed into modified versions of the contribution of technical change and the effect of the variations in the scale of production. This framework has been applied to the study of the Spanish electric sector from 1985 to 1996, during which relevant regulatory changes were introduced in order to increase productivity. For this, a normalized quadratic cost function was estimated. The results show important productivity gains with both technical change and scale effect playing important roles.

On the Specification of Indirect Utility and Willingness to Pay for Discrete Residential Location Models

In this paper we develop a framework to describe the individual choice of residential location using the microeconomics of discrete choices. The individual is seen as deciding frequency, duration, and location of a set of activities for each potential residential zone, knowing the distribution of goods and activities in space as well as transport costs and travel times. The conditional indirect utility function and its associated willingness to pay function for each zone are obtained, where the roles of accessibility, income, and neighborhood attributes emerge clearly. Zonal utility in discrete location choice models can be specified and interpreted using these functions.

CONSUMER'S SURPLUS AND THE VALUE OF TRAVEL TIME SAVINGS

The implications of evaluating travel time savings from changes in consumers surplus derived from discrete choice models are examined, and this approach is related to and compared with the standard procedure based on time pricing.

VALUATION OF USERS' BENEFITS IN TRANSPORT SYSTEMS

Transport projects involve costs and benefits. Benefits to users appear in the form of more and/or better trips. Once the neoclassical idea of demand is accepted, the variation of utility levels underlie the measurement of benefits. In the evaluation process, benefits have to be compared with costs, and this can be done converting utility into monetary units. This paper deals with the treatment of this problem, starting with the general relation among utility, demand and the various forms of consumers’ surplus, to move further into the particular forms that these relations take in the transport field. The rule‐of‐a‐half is followed from the intuitive initial justification to a strict (and general) analytical derivation. More rigorous forms of users’ surplus variation are then presented for fairly general cases, including both aggregate and disaggregate transport demand models, emphasizing the manner in which welfare measures are derived in each case. Discussion is centred around the comparative advantages...