MODELLING GEOMETRIC DESIGN OF A RING ROAD AS A TRAFFIC CONGESTION MITIGATION STRATEGY FOR RAILWAY LEVEL CROSSING

Abstract

Railway level crossings on primary arterial roads frequently cause significant congestion due to regular train movements, resulting in long queues and disruption at nearby intersections. This study proposes a geometrically designed ring road as an alternative traffic network to reduce congestion along the Kadungora–Garut corridor in West Java, Indonesia. A quantitative engineering approach was applied by integrating multi-criteria route screening, constraint-based geometric design, and traffic performance analysis. Route selection considered topographic, geological, environmental, land acquisition, and traffic factors, followed by detailed horizontal and vertical alignment design in accordance with Indonesian highway standards. The proposed ring road is 2.95 km in length and designed as a 4/2D facility with a design speed of 80 km/h, serving a projected average daily traffic (LHRT 2024) of 13,145 smp/day. The alignment includes five Spiral–Circle–Spiral horizontal curves and six vertical intersection points that meet geometric requirements for curvature, gradients, and stopping sight distance. Traffic evaluation shows that diverting through traffic to the ring road can reduce queue lengths at the railway crossing by approximately 45–55% during peak hours and improve the level of service from E to C. The alternative route also provides travel time savings of 6–9 minutes per vehicle during train closures while limiting congestion spillback. The selected alignment primarily crosses agricultural land, reducing land acquisition impacts and associated costs, demonstrating the effectiveness of constraint-based ring road planning for improving intercity traffic performance.