Transversal stability of road profiles in urban contexts: a case-study

The survey of the longitudinal profile of road pavements is a crucial operation when evaluating the superstructure conservation state. For a correct and accurate verification of evenness, it is necessary that the alignment chosen for the acquisition of profilometric data is as representative as possible of the real road surface, which doesn’t always prove to be the case, especially in urban areas. This emerges more clearly in profilometric surveys conducted with the ARRB Walking Profiler (characterised by a preset data acquisition step of 24 cm, in correspondence to the mega-texture wavebands), the sensitivity of which requires detailed attention. The study reported in this paper investigated the effects of randomness or stability of the profilometric surveys of road surfaces along parallel longitudinal alignments in different urban road contexts. The acquisition, and successive numerical processing of the profilometric data also allowed the variability and stability to be verified of the evenness indexes currently used in a transverse direction with respect to the platform (IRI, RN, MRI, RMS, PSD). The profilometer used was the Walking Profiler, an instrument produced by ARRB Transport Research following the World Bank specifications for Class I profilometers. The profilometric data acquired using the ARRB Walking Profiler were then downloaded and analysed using the software ProVAL (Profile Viewing and AnaLysis), an application sponsored by the US Department of Transportation, as well as the Federal Highway Administration (FHWA) and the Long Term Pavement Performance Program (LTPP), and specifically built to allow the users to make a diversified analysis of the longitudinal profiles of pavements.