Publications

Following his internship with the Institute for Policy Research (IPR), Jac co-authored a paper which investigated the impact of inclement weather on the service stability, efficiency, and feasibility of mass-transit bus operations delivered by fully electrified fleets.

The objective was to provide easy to interpret results from a real-world case study that would reduce some of the uncertainty operators face when decarbonising their fleets. The regression results suggest that higher wind speeds and lower temperatures positively correlate with energy consumption and negatively correlate with the total energy regeneration rate. This effect is especially pronounced at freezing temperatures. 

The implication of these results is that through their impact on energy consumption and vehicle range, weather effects will influence the profitability of fleet electrification as well as the optimal fleet size, charging infrastructure, and route schedule.

The decarbonisation of the transport sector is central to the UK's net-zero strategy. This study evaluates the economic viability of depot-charged single-decker electric bus fleets by integrating vehicle, crew, and charging scheduling into a total cost of ownership analysis.

Our results indicate that today's electrified bus fleets are roughly cost comparable to their traditional diesel counterparts. However, the cost disparity varies depending on the timetabling scenario, such that smaller operations continue to require subsidisation. 

We conclude that further battery price reductions and a more targeted subsidy system are critical to bridging the cost gap between the two propulsion technologies in a way which maximises taxpayers' value for money.

The electrification of bus fleets is central to achieving low-carbon transport, yet uncertainties remain around whether electric buses can deliver reliable and cost-effective operations for all types of operators. While previous studies emphasise their lower fuel and maintenance costs, limited attention has been given to the economic implications of vehicle downtime.

This study investigates how electric bus availability influences fleet size requirements and subsidy needs. Using detailed maintenance and downtime data from a UK bus operator, we apply a total cost of ownership (TCO) framework combined with a probabilistic model of bus availability over a 20-year period.

Our analysis shows that although electric buses incur lower maintenance expenditures, their reduced availability substantially increases the number of spare vehicles required, raising capital costs – especially for smaller or rural operators. For example, electric fleet size requirements increase by roughly 18 to 23% per 10-percentage-point shortfall in availability relative to the diesel fleet benchmark.

Policy simulations indicate that that if availability has not improved since 2020, then today’s operators will require procurement grants of between 35.7 and 45.0% depending on the scale of operation – and will continue to require additional financial support beyond 2040. Whereas, if availability has and continues to improve, the procurement grants required by today’s operators fall to between 30.7 and 39.7%, with no procurement grants necessary past 2032.

These results highlight that vehicle availability is a critical but underappreciated factor in fleet electrification and should be explicitly incorporated into both cost analyses and subsidy design.