Mavromatis S., Papadimitriou E., Yannis G., Psarianos B., “Modeling stopping sight distance on left-turn curves of freeways overlapped with crest vertical curves”, Proceedings of the 95th Annual meeting of the Transportation Research Board, Washington, January 2016.

This paper investigates potential Stopping Sight Distance (SSD) violation for 130km/h vehicle speed, on the passing lane of left curved, divided highways overlapped with crest vertical curves. The authors previously developed a SSD control methodology that relates concurrently the 3D configuration of a roadway to the dynamics of a vehicle moving along the actual roadway path, which is applied for the assessment of critical design parameters directly related to both demanded and available SSD values. Initially, by utilizing control geometric and driver – obstacle values adopted by AASHTO 2011 design policy, excessive SSD inadequacy areas were revealed. Subsequently, on the basis of a classic statistical and explanatory modeling approach for a number of geometry parameters, an evaluation of SSD sufficiency was carried out in terms of both the probability of SSD inadequacy and the prediction of the object height in order to grant SSD adequacy (amended object height). These models may be useful to researchers and practitioners aiming to evaluate the interaction of the utilized design parameters in terms of the presence and the extent of SSD deficiency. The results suggested that the probability modelling approach was efficient, yielding a model which enables to correctly assess SSD adequacy (by more than 94%) in such 3D road alignments. The lognormal modelling approach for the prediction of the amended object height (AOH) was proved somewhat less accurate when the AOH exceeds 1 metre, and further analysis is required in order to fully investigate the non-linear relationships between the examined variables and the amended object height.