Speed reduction effectiveness by elevations in Vienna

Abstract

Traffic safety is a global problem, as conflicts occur due to functional overlapping of the infrastructure, different system speeds and space requirements of various road users. Non-adapted speed is one reason for fatal accidents. Reducing speed, e.g. through traffic calming measures, can save lives. The objective of this thesis is to demonstrate the impact of elevations to traffic safety, form recommendations for their arrangement, design and construction as well as to question their future significance with technical innovations and autonomous vehicles. 40 elevations (elevated roadways) – ten per type – were selected through the city area of Vienna for executing speed measurements. Using a laser rangefinder, two speeds per elevation and vehicle were measured – the initial and undisturbed speed at sufficient distance to the elevation and the speed at the primary ramp of the elevation. The effectiveness was evaluated using the achieved speed reductions. Greater speed reductions were observed with higher initial speeds. Visual perception, e.g. of a tighter lane due to oncoming traffic (+20 [%]) or differing surface material (+38 [%]), unlike dimensions, has been determined to have a great influence on speed reduction and therefore on enhancing traffic safety.

Traffic safety is a global problem, as conflicts occur due to functional overlapping of the infrastructure, different system speeds and space requirements of various road users. Non-adapted speed is one reason for fatal accidents. Reducing speed, e.g. through traffic calming measures, can save lives. The objective of this thesis is to demonstrate the impact of elevations to traffic safety, form recommendations for their arrangement, design and construction as well as to question their future significance with technical innovations and autonomous vehicles. 40 elevations (elevated roadways) – ten per type – were selected through the city area of Vienna for executing speed measurements. Using a laser rangefinder, two speeds per elevation and vehicle were measured – the initial and undisturbed speed at sufficient distance to the elevation and the speed at the primary ramp of the elevation. The effectiveness was evaluated using the achieved speed reductions. Greater speed reductions were observed with higher initial speeds. Visual perception, e.g. of a tighter lane due to oncoming traffic (+20 [%]) or differing surface material (+38 [%]), unlike dimensions, has been determined to have a great influence on speed reduction and therefore on enhancing traffic safety.