National Institute for Transportation and Communities

PRESENTATION ARCHIVE

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OVERVIEW

Although connected vehicles (CVs) will soon go beyond testbeds, CVs and human-driven vehicles (HVs) will co-exist over a long period. Hence, it is critical to consider the interactions between these two types of vehicles in traffic flow modeling. In this study, we aim to develop a macroscopic model to understand how CVs would impact HVs in the traffic stream. Grounded on the second-order traffic flow model, we study the relationships among flow, density, and speed by two sets of formulations for the groups of CVs and HVs, respectively. A set of friction factors, which indicate CVs' impact to HVs, are introduced to the speed equation for accounting CV speed impacts. Then extended Kalman Filter is employed to update both model parameters and friction factors in real-time. By using CVs trajectory data as measurements, the difference between CV average speed and overall traffic mean speed will be fully accounted. The proposed model will serve as a basis for designing CV-based traffic control function,...

The proliferation of information technology in the transportation field has opened up opportunities for communication and analysis of the performance of transportation facilities. The Highway Capacity Manual relies on rules of thumb and small data samples to generate levels of service to assess performance, but modern detection technology gives us the opportunity to better capture the dynamism of these systems and examine their performance from many perspectives. Travelers, operations staff, and researchers can benefit from measurements that provide information such as travel time, effectiveness of signal coordination, and traffic density. In particular, inductive loop detectors show promise as a tool to collect the data necessary to generate such information. But while their use for this purpose on restricted‐access facilities is well understood, a great many challenges remain in using loop detectors to measure the performance of surface streets.

This thesis proposes 6 methods for estimating arterial travel time. Estimates are compared to simulated data visually, with input/output diagrams; and statistically, with travel times. Methods for estimating travel time are applied to aggregated data and to varying detector densities and evaluated as above. Conclusions are drawn about which method provides the best estimates, what levels of data aggregation can still provide useful information, and what the effects of detector density are on the quality of estimates....

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...

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