Alternatives to Improve Operational Traffic in Roundabouts Using Microsimulation

Abstract

Roundabout in urban arterials are likely to block roads or generate long queues of vehicles due to the constant changes on urban dynamics near to the interception. Several alternatives to modify the flow pattern or geometry and infrastructure need to be study previously to propose a final design solution of roundabout with traffic issues. In this study, a review of three alternatives to improve the operational traffic are discussed; signalized intersection, turbo-roundabouts and overpass/underpass. In addition, the application of these alternatives is evaluated in a “classic” roundabout located at Tunja city that has a maximum of 3691 Veh/h counted and it is operated in saturated condition.  Microsimulation is used from a calibrated model with volume counted, vehicle composition and speeds in the VISSIM software. Results show that signalize the roundabout does not improve the operational traffic (with a reduction on 38% of approach speed) and, the turbo-roundabouts are a mid-term solution that meet the traffic demand on 15 years with a progressively loss of service (with a  mean approach speed of 6.4 Km/h at 15 years). The constructions of underpass and overpass show to be the only solution that increase four times the travel speed throw the roundabout and keep acceptable speed at the end of cyclic live of intersection (18.7 Km/h at 20 years).