On November 28th, 1996, the first Dynamic Route Information Panel (DRIP) displaying travel times in the Netherlands was brought into operation on the A13 motorway between The Hague and Rotterdam. The DRIP displays current travel times from the Ypenburg interchange to the Kleinpolderplein interchange. An algorithm referred to as the travel time estimator has been developed to estimate the current travel time from measured traffic data. In this study, the following three aspects of the travel time estimator are further analysed: (1) `recovery effect': in a number of cases, after traffic congestion has practically cleared up, the estimated travel time actually increases again; (2) `lag effect': the estimated travel time shows a structural lag of a number of minutes in comparison with the travel time actually observed; and (3) the difference between methods for estimating travel times, namely: a `speed method' (based on measured speeds) versus an `intensity method' (based on measured intensities). See also C 11074 (IRRD 491589) and C 7432 (IRRD 888695).
Samenvatting