Large-scale network modeling using the Macroscopic Fundamental Diagram (MFD) is widely based on the single-reservoir model, where the variation of the accumulation of circulating vehicles in the reservoir equals inflow minus outflow. This simple accumulation-based model suffers from the infinite-wave speed dropback, which is problematic when the inflow varies rapidly. To overcome this limitation, a trip-based model has been recently proposed, but whose solution cannot be obtained analytically.