How can transfer times be included when calculating travel times?

[FlorianNachtigall]

Motivation: I would like to calculate realistic average travel times across the transit network to calculate meaningful closeness and betweenness centrality measures.

Issue: For realistic travel times, I need to consider the transfer times. However, with the current implementation I believe it is not possible to determine whether a transfer is needed between edges that are connected by the same node (stop_id). With other words, the information whether two adjacent edges belong to the same actual route or not is lost.

Approach: My initial idea was to increase the length (travel time) of walking edges by the average boarding_costs of adjacent nodes. However, for edges that connect the same node but in reality belong to different routes / transit lines, no walking transfer edges are added to the network and consequently transfer times are not included with my approach included.

So, how would you propose to include the transfer times when calculating travel times and centrality metrics?

Thanks, happy about any suggestion!