Transactions on Transport Sciences

Transactions on Transport Sciences X:X

Enhancing Urban Mobility: A Road Diet Approach to Improve Traffic Capacity and Pedestrian Safety

Kusuma R. Haratama^a, Peter Furth^b, Anita Susanti^a

^a. Department of Transportation Engineering, State University of Surabaya, Surabaya 60231, Indonesia

^b. Civil and Environmental Engineering, Northeastern University, Boston 02115, USA

Urban intersections often face the dual challenge of managing high traffic volumes while ensuring pedestrian safety. This study investigates whether road diet strategies—reducing travel lanes while reallocating space for pedestrians—combined with signal timing optimization, can improve both vehicle throughput and safety at complex urban intersections. The North Washington Street corridor in Boston, including City Square and Keany Square, was selected due to its congestion and long pedestrian crossing distances. Data were collected via sensors and manual counts in December 2022. Microscopic simulations were conducted in PTV Vissim, calibrated to field observations within ±5% accuracy. The intervention included lane reductions, a new northbound receiving lane, pedestrian refuge islands, split crossings, and revised signal timing using VisVAP. Results show average vehicle delays decreased from 171.97 to 31.12 veh-s at City Square and from 146.60 to 64.88 veh-s at Keany Square. Queue lengths dropped by over 50%, and intersection capacities rose by 34.59% and 24.98% respectively. Pedestrian exposure times were cut significantly, particularly at long crossings. These findings challenge conventional assumptions about road diets limiting capacity. Instead, the combined approach fostered safer and more efficient intersections, suggesting that balanced urban mobility can be achieved through thoughtful design. The study provides a replicable model for cities pursuing Vision Zero and sustainable mobility goals.

Keywords: Road diet; urban intersection design; pedestrian safety; traffic signal optimization; urban mobility.

Received: May 13, 2025; Revised: August 4, 2025; Accepted: September 2, 2025; Prepublished online: February 23, 2026