Involving the private sector in tramway track network maintenance: case study of the City of Rome

A concern of several municipalities is to find the most economic way to keep their tramway track network at acceptable performance levels. This paper uses as a case study data from the City of Rome to estimate the annual cost for the municipality to carry out track network maintenance using the private sector through a form of public private partnership (PPP). Assuming that the private sector partner will be selected through a competitive bidding procedure, it is essential that the municipality carry out a preliminary study to estimate a reasonable level of annual payment required to compensate the private company for the services rendered during the concession life. This paper uses a recently developed financial model to simulate the project financing under several performance levels or standards, specified as the maximum allowed vertical displacement of the rail surface or in terms of the root mean square displacement, both related to a specified spatial wavelength. For each specified level of service, the minimum annual payment to the concessionaire is calculated using the model. The paper assumes that, in view of the relatively poor existing condition of the network, the concessionaire will be required to carry out a replacement of the existing track in the first year of the concession. Two different types of replacement will be investigated. Following the replacement, maintenance operations are carried out through different frequencies of rail grinding, defined as a function of the performance standard specified.