How good in practice are models which estimate traffic delays due to roadworks?

QUADRO 2, the up-dated version of an earlier computer program for the calculation of delays due to roadworks was released by the department of transport in 1982 and, at a PTRC meeting later that year, it was presented as being a powerful tool for use by transport planners and highway engineers. Previously, in 1981, traffic engineering and control reported on a computer program (delprog) which had been developed by Jamieson Mackay and partners to perform similar functions to QUADRO. This paper discusses the practical application of both delprog and QUADRO 2 and their suitability to take account of difficult site specific parameters. Both models have now been extensively used and the paper highlights the testing procedures which have been applied to validate the models to a local situation and illustrates the sensitivity of various input parameters such as the programme of maintenance jobs; the traffic profile and its composition and growth assumptions; diversion routes and their characteristics; speed/flow relationships; delay characteristics and incident and accident assumptions. The benefits to be derived from undertaking such delay computations in the context of the traffic and economic planning for a major highway route are illustrated, but the need for up-to-date and realistic default values and the introduction of suitably measured and monitored local values is noted.(a) for the covering abstract of the proceedings see IRRD 274491.