Indo_HCMSDP: An open-source package for signal control design using Indo-HCM guidelines

US-Highway Capacity Manual and Webster method remains the most popular methods for performance assessment of signalized intersection for homogenous traffic conditions. Owing to the limited scope of the abovementioned methodologies for Indian mixed traffic conditions, the Indian Highway Capacity Manual (Indo-HCM) lays guidelines for the performance assessment of isolated fixed-time signalized intersections. The manual, however, does not include a design framework for signalized intersections. Furthermore, the current state-of-the-art IRC: 93-1985-based signal control design has applicability constrained to undersaturated intersections. Based on the recommendations of Indo-HCM and IRC: 93-1985, this study aims to explore three popular algorithms named n-D Grid Search Algorithm, L-BFGS-B and QSP to estimate the optimum signal phase plan. The study aims to develop an open-source python package, “Indo_HCMSDP”, to assist practitioners with signal design applications. The package contains three signal design tools, namely Indo_HCMSDT_I, Indo_HCMSDT_II and Indo_HCMSDT_Adv. Using a case study of two closely spaced intersections in Surat city, the study highlights the applications and limitations of the three aforementioned tools.

I. Introduction

Intersections are critical nodes in transportation networks. Complex intersections result from continuous development and alterations in urban areas to meet latent demand for the movement of people and goods. Traffic management at these complex intersections is a critical challenge for transportation planners, especially in the urban setting. Because of their proclivity to occupy the same space simultaneously to manoeuvre, such intersections pose safety hazards to road users, including pedestrians, and controls must be exercised at various levels to ensure safe and efficient movement. The type of control chosen is determined by land use, geometric characteristics, and prevailing or anticipated traffic conditions. Webster's method is one of the most popular methods to evaluate signal-controlled intersections and design controls. Webster's model, however, fails to predict the delays as the ratio of volume to capacity (v/c ratio) nears 1. Another model named the over-flow delay model is valid only above a v/c ratio of 1.15 [1].