ApolloChoiceModelling forum

Hi,

I am trying to estimate a mode share between road and rail alternatives, however, there is a capacity constraint for the rail alternative. That is, the freight terminal for the rail alternative has a limited capacity and once it reaches capacity, it cannot accept any more rail trips (and this additional freight is loaded onto trucks on road). In such a situation, I assume estimating market shares for the two alternatives may not be correct, without considering capacity at the terminal for the rail alternative.

One solution could be to add some type of congestion function to the utility function of rail alternative (and iteratively check the capacity to actual demand ratio to achieve convergence).

I would be very interested in your opinion regarding estimating mode share under capacity constraints, and if possible, could you please advise if there is any literature available in discrete choice modelling that examines such issues.

Many thanks.

Best,
Fayyaz

Hi Fayyaz

in your data that you use for estimating the model, do you know when capacity has been reached? In that case, the easiest option would be to work with availabilities

Stephane

Thanks for the suggestion, Stephane. I believe my approach was not correct, as I was adding capacity to the demand model instead of the supply model. I have now solved the issue (using user equilibrium). Many thanks.

Fayyaz