Off-Ramp Coupling Conditions Devoid of Spurious Blocking and Re-Routing

TL;DR

This paper introduces FIFOQ, a new coupling model for highway traffic networks that avoids spurious re-routing and maintains realistic flow conditions at off-ramps, improving upon existing FIFO and non-FIFO models.

Contribution

The paper proposes FIFOQ, a novel coupling condition for traffic flow models at off-ramps that prevents unrealistic re-routing while preserving key properties of non-FIFO models.

Findings

FIFOQ prevents spurious re-routing of vehicles.

It maintains realistic flow conditions at off-ramps.

The model improves traffic simulation accuracy.

Abstract

When modeling vehicular traffic flow on highway networks via macroscopic models, suitable coupling conditions at the network nodes are crucial. Frequently, the evolution of traffic flow on each network edge is described in a lane-averaged fashion using a single-class Lighthill-Whitham-Richards model. At off-ramps, split ratios (i.e., what percentage of traffic exits the highway) are prescribed that can be drawn from historic data. In this situation, classical FIFO coupling conditions yield unrealistic results, in that a clogged off-ramp yields zero flux through the node. As a remedy, non-FIFO conditions have been proposed. However, as we demonstrate here, those lead to spurious re-routing of vehicles. Then, a new coupling model, FIFOQ, is presented that preserves the desirable properties of non-FIFO models, while not leading to any spurious re-routing.