A methodology to measure sight-hidden dips’ parameters

• A procedure to measure sight distances in roads has been developed.
• The procedure is based on photos taken in a road.
• An application to a sight-hidden dip has been made.
• In the case study, mean square error is circa 1 m, below estimated errors.

Highway design standards specify several requirements on available sight distance. Usually, compliance with these standards is ensured during the design phase of a new road. This is made through geometric calculations that take into account the terrain and the road. In this paper, a procedure for measuring distances in an existing road from georeferenced photographs is proposed. In addition, an estimation of the error committed when using this procedure is made. Distances measured using this procedure are compared with the ones measured using a Global Navigation Satellite System (GNSS). Distances error is within the error estimation and is low enough for using it in traffic safety studies. In addition, the procedure is applied to measure several parameters of a sight-hidden dip. This procedure does not need a terrain model to measure these parameters. This is an advantage compared with other existing procedures for estimating the parameters of sight-hidden dips.