Clear zones in urban environments

Abstract

[Abstract]: Run off road accidents are global problems, with fatal and serious injuries reported for speeds of 40 km/hour and above. Frequency and severity of these injuries can be significantly impacted by providing a safe roadside environment. This can be achieved by ensuring the area adjacent to the roadside is free of obstacles, hazards and distractions and is designed to maximise drivers' opportunity to regain control of an errant vehicle. A 'clear zone' is the total width from the traffic lane edge required to be clear of roadside hazards. A variety of hazards may occur within the specified clear zone including point and continuous hazards. There is still some conjecture about the diameter size of trees and poles to be classified as hazards. A hierarchy of treatments exists with six different methods recommended. Practicalities of treatments in urban areas must be considered. Questions arise about the classification of hazards and the inherent risks associated with their presence, including the treatment of new infrastructure versus current treatments of existing rigid objects and potential hazards in specified clear zones. To meet legal requirements, road authorities must fulfil their duty of care to road users. They must not create a foreseeable risk of harm and are obliged to take reasonable steps to remedy an existing risk within a reasonable time. The court recognises that resources are limited, including man power and funding. Road authorities need methods in place to prioritise projects to address safety issues. Quantitative and qualitative assessments are required to prioritise and assess the engineering, environmental and social ramifications of safety concerns and proposed treatments. Designers and engineers are reluctant to make subjective decisions that may not be supported by standards. Practical treatment solutions must be ‘fit for purpose’. The conclusion of this paper provides tools that designers and engineers can use to assist the evaluation process.