Generalised cost

[3] Monetary (or "out-of-pocket") costs might include a fare on a public transport journey, or the costs of fuel, wear and tear and any parking charge, toll or congestion charge on a car journey.

Non-monetary costs refer to the time spent undertaking the journey.

The generalised cost function can be expanded to reflect this congestion delay.

Typically, although travellers "dislike" all time spent travelling, they dislike walking and waiting parts of the journey more than in-vehicle journey time, and thus would be willing to pay more to avoid them.

The function u(w) mentioned earlier can therefore be considered to consist of differing sets of valued time.

Once the equivalent in-vehicle time for the whole journey is calculated, this can be converted to a monetary value as described earlier.