Methodology for Evaluating the Operational Performance of Interchange Ramp Terminals

Abstract

Interchange ramp terminals are critical components of the highway network. They provide the connection between various highway facilities (e.g., freeway–arterial and arterial–arterial), and their safe and efficient operation is essential. The objective of this research was to develop improved methods for capacity and quality-of-service analysis of interchange ramp terminals. The research focuses on at-grade intersections but not on the freeway proper. All geometric configurations and interchange types except trumpet interchanges are considered, and the scope of the research includes only signalized interchanges and not “Stop” sign–controlled interchanges and roundabouts. The development of the analytical methodology is primarily based on simulation. The reason for using simulation is that adequate samples of field data are not available, and it is prohibitively expensive to collect them for all types of interchange configurations. The research team assessed several simulation models that were identified as capable of simulating all types of interchange ramp terminals and selected the most appropriate one for model development. Once a simulation model was selected, a variety of interchange configurations were simulated, and selected measures of effectiveness were obtained. Analytical models were developed on the basis of the results of simulation to predict different measures, such as average control delay, volume-to-capacity ratio, and queue-to-storage ratio, for a variety of design and traffic control characteristics.

Failure of classical traffic flow theories: Stochastic highway capacity and automatic driving

“…In contrast, after traffic breakdown has occurred the flow rate can remain as large as in an initial free flow (Fig. 1 (d)) 2 [5,6,7,8,9,10,11,16,17].…”

“…Beginning from the classical work by Greenshields [1], a great effort has been made to understand the empirical features of traffic breakdown (see, e.g., [2,3,4,5,6,7,8,9,10], [11,12,13,14,15,16,17]). Traffic breakdown at a highway bottleneck is a local phase transition from free flow (F) to congested traffic whose downstream front is usually fixed at the bottleneck location (Fig.…”

“…Traffic breakdown at a highway bottleneck is a local phase transition from free flow (F) to congested traffic whose downstream front is usually fixed at the bottleneck location (Fig. 1 (a, b)) [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. In three-phase traffic theory, such congested traffic is called synchronized flow (S) [200,201].…”

“…1 (c)). For this reason, traffic breakdown is also called speed drop or speed breakdown [2,3,4,5,6,7,8,9,10,11], [12,13,14,15,16,17]. In contrast, after traffic breakdown has occurred the flow rate can remain as large as in an initial free flow (Fig.…”

“…Highway capacity is limited by traffic breakdown, i.e., a transition from free flow to congested traffic [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. Traffic breakdown with resulting traffic congestion occurs usually at a road bottleneck (see, e.g., [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15], [16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,…”