Donor agencies and recipient governments want to assess the effectiveness of aid-supported sector policies. Unfortunately, existing methods for impact evaluation are designed for the evaluation of homogeneous interventions (‘projects’) where those with and without ‘treatment’ can be...

This paper discusses a number of issues that will become increasingly important nowthat the concept of marginal external cost pricing becomes more likely to be implementedas a policy strategy in transport in reality. The first part of the paper deals with thelong-run efficiency of marginal...

This paper studies the second-best problem where not all links of acongested transportation network can be tolled. The second-best taxrule for this problem is derived for general static networks, so thatthe solution presented is valid for any graph of the network, and forany set of tolling...

We propose a novel statistic for testing the structural parameters in Instrumental Variables Regression. The statistic is straightforward to compute and has a limiting distribution that is pivotal with a degrees of freedom parameter that is equal to the number of tested parameters. It therefore...

For several decades growth of traffic volumes has outstrippedinvestments inroad infrastructure. The result has been a relentless increase intrafficcongestion. This paper reviews the economic principles behindcongestionpricing in static and dynamic settings, which derive from thebenefits...

This paper considers the second-best problem where not all links of a congested transportation networkcan be tolled. The paper builds on earlier work, in which the second-best tax rule for this problem wasderived for general static networks, so that the solution presented is valid for any graph...

In this paper, a dynamic model of road traffic congestion is presented, with an elastic overall demand for morning peak road usage, and with the congestion technology used being 'flow congestion'. It is demonstrated that in such a case, the optimal time-varying toll should include a 'flat',...

In this paper, we investigate congestion caused by differences in desired or possible speeds. Especially outside peak hours, speed differences are probably one of the most important reasons for congestion. Although the model setting, with one lane and no overtaking, may seem simple at first...

We explore the properties of various types of public and private pricing on acongested road network with heterogeneous users and allowing for elasticdemand. Heterogeneity is represented by a continuum of values of time. Thenetwork consists of both serial and parallel links, which allows us to...