In early 2019, RSSB commissioned the Air Quality Improvement Measures project, which carried out a high-level technology feasibility and cost study to explore potential air quality improvement measures for GB rail. The study included technological measures as well as operational and infrastructure measures, both on and off the train. Measures were split into those which reduce emissions at source and measures which reduce exposure.

In summary the study found the most effective ways of reducing emissions throughout the rail network include:

  • retrofit exhaust after-treatment systems
  • reducing the diesel on-time or on-power-time through:
  • selective Engine Shutdown
  • powertrain hybridisation
  • stop-start technology.

It is important to ensure the right type of measures are taken at the right place and that the cost / benefit relationship I fully understood prior to investment. 
RSSB is investigating the various mechanisms possible, in particular feasibility of an incentivisation scheme to encourage to uptake. This includes the determination of the external cost of rail in selected sample areas, so that the overall benefit of any incentivisation scheme can be assessed in net financial terms by comparing external cost against any internal costs associated with the emissions reduction measure and incentivisation costs to promote their adoption.