Innovative interventions for transforming road capacity, safety and emissions on the England's strategic road network

Traffic demand has been forecasted to increase between 24 % to 72 % by 2040 on the England's Strategic Road Network (SRN), exacerbating existing problems relating to collisions, congestion and climate change. This paper aims to identify and investigate innovative interventions to tackle the challenges of improving road capacity, safety and reducing emissions so as to enhance the SRN's performance without constructing new roads. The interventions are categorised in four well-established themes: (i) behaviour and policy, which includes measures such as promoting active travel and public transport usage; (ii) infrastructure, focusing on optimising road and junction design; (iii) connectivity and automation, such as dynamic lane management; and (iv) sustainability, encompassing both harnessing renewable energy sources within the road network and the reduction of emissions from corporate and road users. A thorough review of academic literature and the analysis of documents published by governments and industry worldwide were undertaken to identify key interventions and assess their potential effects on improving road capacity, safety and emissions reduction, particularly on high-speed road networks. Following the examination of these interventions, they are evaluated against a new comprehensive and holistic framework known as PESTEL denoting Policy, Economic, Safety, Technology, Environmental and Location dimensions. The selected interventions were systematically ranked using the widely adopted Analytical Hierarchy Process (AHP), ensuring a structured and objective evaluation. This holistic methodology would be valuable to network operators who intend to evaluate any intervention, going beyond a standard cost-benefit analysis by attributing a score to each component examined. Furthermore, a time-cost matrix has been established analysing the implementation cost and duration for each of the key interventions. Finally, this paper presents an implementation strategy on how such interventions could be employed within the England's Strategic Road Network.