  Second order macroscopic traffic flow models are able to reproduce the
so-called capacity drop effect, i.e., the phenomenon that the outflow of a
congested region is substantially lower than the maximum achievable flow.
Within this work, we propose a first order model for a junction with ramp
buffer that is solely modified at the intersection so that the capacity drop is
captured. Theoretical investigations motivate the new choice of coupling
conditions and illustrate the difference to purely first and second order
models. The numerical example considering the optimal control of the onramp
merging into a main road highlights that the combined model generates similar
results as the second order model.
