Frannie Humplick

Highway pavement distress evaluation: Modeling measurement error

There has been a proliferation of inspection technologies to quantify distresses on highway pavement systems. These technologies employ varying measurement principles and are subject to measurement errors. Estimates of measurement errors are therefore required in order to select among these techniques, and to get accurate assessments of pavement condition. There is abundant literature concerning techniques available for the numerical study of measurement errors. Available techniques include econometric methods of coping with errors in variables when investigating relationships between variables that have been measured with error; calibration approaches under various measurement conditions; and evaluation of measurement errors due to quantification, by a proxy, of concepts that are not directly measurable or observable. The methodologies employed in these techniques rely on certain assumptions for model development and estimation. These assumptions include the nature of error occurrence, whether systematic or random; the effect of these errors on the measured result, whether multiplicative or additive; and the level of knowledge about the true value of the measured object. Such assumptions may be violated under certain conditions. This paper identifies such situations and develops a generalized measurement error modeling approach, in which existing approaches are special cases. Existing methods are reviewed as to the specification models used to represent measurement errors; the types of errors accounted for in the suggested specification model; the type of errors not accounted for and the biases induced in estimated parameters by ignoring certain error types. The approach developed is capable of quantifying the accuracy of measurement for cases where the true value of the measured object is not known. This is the case in highway pavement distress evaluation as there is no single well-accepted technology which can be used as a proxy for the value for calibration purposes. The methodology developed in this paper explicitly estimates the true value and is applied to the calibration of new technologies for highway distress evaluation.

Decentralized structures for providing roads : a cross-country comparison

Minimizing costs is often cited as essential for optimizing service delivery. Roads are the oldest, most important infrastructure services provided by governments. They require construction, rehabilitation, maintenance, and administration. Various institutional arrangements affect the degree to which costs can be minimized. Drawing on analyses of experiences with decentralized road provision in eight countries, a longitudinal change analysis of Korea, and vertical and horizontal analysis across states and local governments in Germany, the authors found that the impact of decentralization varies depending on which aspect one is considering: the efficiency of producing road services or the impact on road users. Resources costs are concave, increasing first and decreasing at later stages of decentralization. Preference costs are downward sloping, suggesting that road conditions improve as decentralization advances. In short, decentralization entails initial costs, mostly as losses in economies of scale. But those losses can be outweighed by increases in efficiency when the locus of roadwork is closer to the people. The advantages or limitations of decentralization are function-specific: a) maintenance functions are best provided locally; b) to minimize resource costs, construction should be either completely centralized or completely decentralized; and c) administrative activities are more efficiently provided by local units similar to local maintenance units.

Is There an Optimal Structure for Decentralized Provision of Roads

The authors empirically investigate how decentralization affects the efficiency of road provision from the viewpoint of the local goods provider and the road user. The theoretical model: a double cost hidden level effort. They include both user and provider concerns in determining the optimal decentralization level. They find that 100 percent maintenance decentralization produces the most efficiency gains, as quality roads are provided at lower unit costs. There is little justification for central government to be involved in road maintenance. Uniform standards combined with decentralized maintenance remove the incentive to reduce costs and erode most local maintenance efficiency gains. Maintenance is a local activity and should reflect user preferences. Central governments should regulate safety and other network externalities by having a stake in road administration financing, planning, policy setting, safety regulation and other network externalities. Central governments should finance no more than 10 percent of administrative costs. Construction depends on the country. Ensure that contracting procedures are efficient before suggesting decentralization. It is easier for local governments to incorporate user preferences in spending decisions. Similarly, determining where to make investments, deciding how to procure works, and monitoring the quality of construction and maintenance is often done more efficiently locally. The results point to the benefits of decentralized provisions of roads, but many countries contract out maintenance and provision. In that case, it may not matter whether local competitive bidding is carried out by a central or local agency.

Does Multiplicity Matter more than Ownership in the Efficiency of Infrastructure Services

The services from infrastructure systems have, for historical reasons or as a result of specific local contingencies, been totally state-owned in certain countries, entirely privatized in others, and sometimes provided through a mixture of public, private, and self-help arrangements. Many governments are re-evaluating the manner in which services have been provided in the past, and are searching for ways of increasing the efficiency of service delivery. One of the options considered is privatization, whereby a transfer of ownership of infrastructure assets from the public to the private sector is undertaken as a measure to increase efficiency. Another option is introducing multiplicity in the production of infrastructure services by: introducing competition in and for service production; and devolving responsibilities to regional, state, or local authorities.