Proactive Ramp Management under the Threat of Freeway-Flow Breakdown

Abstract

Procedia - Social and Behavioral Sciences 16 (2011) 4-14. doi:10.1016/j.sbspro.2011.04.424Received by publisher: 0000-01-01Harvest Date: 2016-01-04 12:23:45DOI: 10.1016/j.sbspro.2011.04.424Page Range: 4-1

Variable Speed Limit Strategies to Reduce the Impacts of Traffic Flow Breakdown at Recurrent Freeway Bottlenecks

“…When it occurs, it can occur at different times. This stochastic nature of capacity has received a great amount of interest and attention among researchers in two areas: 1) its impacts on a freeway's capacity assumptions (Geistefeldt, 2008;Elefteriadou et al, 2003), and 2) finding the probability of breakdown occurrence based on upstream traffic conditions such as traffic flow, occupancy or combinations of the variables (Elefteriadou et al, 1995, Kondyli, 2011 It is interesting to compare the real-world stochasticity mentioned above with the stochasticity of simulation models, described next. Stochastic simulation models produce different results for simulation runs with the same inputs, but different seed numbers.…”

Development of System-Based Methodology to Support Ramp Metering Deployment Decisions

“…Report 3-87 suggests improving this algorithm by including the probability of breakdown for the activation and/or metering rate calculation (Elefteriadou et al, 2009). This means that the ramp metering rate is set to keep the demand significantly lower than the capacity, as is done with the simple demand-capacity algorithm.…”

“…MALINEA measures upstream occupancy of the freeway segment and the time lag between upstream and downstream measurements in order to incorporate the upstream conditions in the metering rate calculation. MALINEA uses the following equation (Elefteriadou et al, 2009):…”

“…This predictive feature enables the algorithm to prevent bottlenecks. However, inaccurate prediction may lead to poor results (Elefteriadou et al, 2009). Zhang et al (2001) evaluated the performance of SWARM in 2001, with a five-step ahead prediction and reported very poor results compared to the ALINEA algorithm, zone algorithm, and bottleneck algorithm (Zhang et al, 2001).…”

“…NCHRP Report 3-87 suggests enhancing this algorithm by considering the probability of a breakdown threshold for ramp metering activation and the local metering rate calculation (Elefteriadou et al, 2009).…”