Executive Summary : | Annual road traffic deaths have reached over 13 lakhs globally (WHO 2018) and over 1 lakh in India [1.31 and 1.53 respectively in 2020 and 2021 (MORTH 2021)]. Traffic safety analysts have made substantial attempts to create safe roads for years. However, despite prevalent international (Highway Safety Improvement Program, FHWA) and national (NITI Aayog, Bharatmala Pariyojana) advocacy, transport system infrastructures remain unsafe several times. Factors affecting the likelihood of road traffic crashes are driver-vehicle-roadway related. Recently, several studies highlighted the potential association of driver-related factors and found them to play an aetiological role in most road incidents. Driver behavioural factors account for over 90% of road traffic crashes (Dingus et al. 2016, Petridou and Moustaki 2000). Lack of repeated test data in a safe environment while designing highways increases traffic-related deaths and road injuries, making transportation infrastructure unsafe. The hypothesis of the current study describes the impacts of increased cognitive demand on visual tasks in critical visibility conditions. Experimental trials make it apparent that visibility distance for an individual while taking an appropriate decision varies across vehicle speeds, light transmission through the atmosphere, and visual acuity, i.e., the ability of drivers' eyes to distinguish objects. It also points to the fact that drivers' visibility gets significantly affected due to increased cognitive demand in case of rainfall since raindrops on the windshield act as an auxiliary lens and result in the distortion of visual images. Thus, it is evident that besides characteristics of the driver, road and vehicle speed, atmospheric conditions, i.e., the state of the atmosphere in terms of sunshine or downfall in the form of rain and fog, affect safety performance. In addition, the colour of the object and its background (e.g., traffic signs) affect contrast sensitivity, which plays a vital role in drivers' visibility. While a handful of studies have focused on visibility aspects, the effectiveness of traffic signs in different visibility conditions is not well developed. An extensive change in traffic dynamics in the era of new-generation automobiles further underpins such complications. Towards addressing this challenge, the proposed research team has conceptualized the idea of performing controlled experiments in critical visibility conditions by setting up a low-cost driving simulator and calibrating it properly to generate a valid indigenous substitute for actual driving under local roadway conditions. A safe environment would also enable repeated trials and testing reliability to see the degree of safety across varied driving and visibility conditions. |