01628766

Component

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, the authors 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. Analytical solutions are presented for the single reservoir loading problem with a family of demand functions useful to model rush hours; and for the same problem including user equilibrium with constant total demand. The authors find that under constant demand and suitable transformations (i) the solution depends on a single parameter (ii) the solution is very similar to the single MFD loading problem, which has two steady-state solutions, one of which is gridlock, and (iii) the varying length model is similar but gridlock does not happen; its steady-state solution is independent of surface network parameters. These parameters do affect the rate of convergence to the steady-state solution, but the authors find that convergence rates are virtually identical when time is expressed in units of the MFD free-flow travel time.

This paper was sponsored by TRB committee AHB45 Standing Committee on Traffic Flow Theory and Characteristics.

01618707

17-04531

English

13p

2017

Transportation Research Board 96th Annual Meeting

Digital/other

Figures; References

Dynamic traffic assignment; Equilibrium (Systems); Freeways; Macroscopic traffic flow; Peak hour traffic; Traffic congestion; Travel time; Urban areas

Highways; Operations and Traffic Management; Planning and Forecasting

Transportation Research Board Annual Meeting 2017 Paper #17-04531

TRIS, TRB, ATRI

Dec 8 2016 11:44AM