Research into braking values for freight reveals new paths and better reliability
ETCS has default values for brake performance. These are based on train characteristics and capabilities. However, the use of default braking values can underestimate freight braking capability. This restricts their speeds unnecessarily.
The introduction of ETCS also unlocks the potential to assign permissible speeds on a train-by-train basis. Such values depend on train braking performance and other factors.
There is an industry proposal to use a default braking value for freight. This is based on minimum braking requirements. However, the impact of this was unknown. Therefore, research about this issue was needed.
RSSB research compared different approaches that could be used in ETCS for brake performance values.
Vehicle-specific braking values were compared with the use of a default value. The benefit for vehicle-specific values depends on the route used. The South West Main Line (SWML) was used as the case study route. On the SWML, default braking values did not provide much benefit over vehicle-specific braking values.
Further work will be needed to establish the case on other routes using the approach developed by this research.
The research also showed a feasible case for introducing freight differential speeds. This can be done in advance of ETCS.
Industry now has a more complete understanding of the impact of default braking values for freight, informing the migration to ETCS.
The most notable finding is the opportunity for freight speed differentials that the work identified.
This could allow freight formations that meet defined characteristics to travel at higher speeds. This, in turn, may enable new freight paths and increase the reliability of freight services.
Follow-on research (T1348) is now pursuing this significant opportunity.