This paper investigates the dynamic user equilibrium with two alternative routes, a freeway with a fixed capacity and the surrounding city-streets network, modeled with a macroscopic fundamental diagram (MFD). Apart from the traditional approach of constant network and trip lengths for the MFD, we propose a dynamic formulation of these quantities, which grow with the congestion level on the surface network to reflect that off-ramp capacities are finite and the length of the freeway exit section, dynamic.