The road transport investment model has been developed by the Transport and Road Research Laboratory to aid investment decisions within the roads sector in developing countries. The model calculates construction, maintenance and road user costs over the 'life' of the project from information provided by the user and using relationships which are discussed fully in TRRL laboratory report 674. This report is the draft user manual for the road transport investment model. It describes how the model can be used for project appraisal and discusses its applications and its limitations. The input required for the model is described in detail and output is illustrated by the use of two case studies. A list is also given of all the messages that the model prints and the action needed in each case. An appendix to the report contains details of the model's operation including all the relationships and constants used. A further appendix gives details of the program's computer requirements and gives guidance for mounting the program on a computer. A list of definitions, conventions and data limitations are given as another appendix and additional appendices give a summary of the input requirements and also the 'minimum' input requirement to help new users of the model. A Fortran listing of the computer program is not provided, but this is issued by the department of the environment highway engineering computer branch. (Author/publisher).
Abstract