An Analytical Derivation of the Capacity at Weaving Sections

Wednesday, November 20, 2013, 11:00am to 12:00pm PST
Florian Marczak, University of Lyon

PSU Special Transportation Seminar:

An analytical derivation of the capacity at weaving sections consistent with empirical observations and micro-simulated results

Where: ITS Lab, Room 315, PSU Engineering Building

Summary: Weaving sections are discontinuities of the highway network formed when merge segments are closely followed by diverge segments. Because of their geometrical configuration, weaving areas generate numerous lane changes. Those lane changes lead to a reduction of the capacity and affect therefore the operation of weaving sections. 

This contribution aims at investigating empirically the lane changing behavior at a weaving section located in Grenoble (France). The data have been collected at a microscopic level, describing the position of every vehicle at every time step (trajectories of each individual vehicle). The data have been measured with a high-resolution camera mounted underneath a helicopter. 

From the empirical results, we develop an analytical formulation of the capacity of weaving sections. We consider a theoretical weaving section as the superposition of two merges and two diverges. We assume moreover that the accelerations and slowdowns of weaving vehicles create voids in the traffic stream that reduce the total capacity. The analytical estimation of the capacity is compared with field macroscopic data measured in Grenoble and micro-simulated results.

The specification of the needed data sample to extrapolate the results obtained in Grenoble is presented in the last part of the talk. To test the analytical model to other weaving sections and increase its predictive power a key step is to gather individual data from loop detectors. The last part of the talk presents therefore some typical detection configuration to this aim. 

Florian Marczak received his engineering and master degrees in Civil Engineering in 2011. He is currently a PhD Student at IFSTTAR (The French Institute of Science and Technology devoted to Transport, Planning and Network) and is affiliated to the University of Lyon. He investigates at both empirical and analytical points of view the mechanisms that trigger congestion at the discontinuities of the highway network.