Saving space in a dense city: When designers should consider the new nano-interchange

Abstract

In the dense cities of developing countries, freeway designers need to provide large capacities in small areas. The nano-interchange, a new system interchange, attempts to address this challenge. The authors designed each alternative at 35, 45, and 55 mph ramp design speeds. The designs revealed that the nano-interchange saves space for any given ramp speed, and the construction plus right-of-way costs may not be much higher than the four-level. Operation estimations showed small travel time savings for the four-level interchange at any particular design speed. Safety evaluations indicated that the nano-interchange will likely cause more reported collisions at ramp junctions. Overall, designers should consider the nano-interchange when they want to keep ramp design speeds higher, but designers willing to reduce ramp design speeds will find the four-level a tough competitor.