Currently many railway companies operate on a mixed infrastructure, i.e. trains with big speed differences (e.g. freight and high speed passenger trains) run on the same tracks. This has a number of drawbacks: low capacity, additional infrastructure costs for passing lanes etc.

Therefore infrastructure operators try to “demix” their infrastructure by restricting trains to different tracks according to average speed. Figure 1 shows (in a very simplified manner) the principle of line demixing and the consequent increase in line capacity.

This can be a way to increase system capacity without investing in new infrastructure, thus lowering specific infrastructure costs.

Presently many railways recur to temporal demixing, i.e. freight trains running during night hours, passenger trains during day-time. In many cases, the spatial demixing described here is however a much better and much more customer-friendly strategy.

Figure 1: Principle of line demixing and capacity effect (simplified)

Source: IZT