Traffic Operations and Management

This work explores the problem of estimating road link densities from cellular tower signals by mobile subscribers in urban areas. The authors pose the estimation problem as a quadratic program, and present a robust framework that produces vehicle density estimates and is suitable for large-scale problems. The authors demonstrate that both simple and sophisticated models of cellular network connections can be handled robustly by the framework, without sacrificing efficiency or scalability. The authors present a numerical experiment on the I-15 corridor in San Diego based on a...

We consider the equilibrium departure time problem for a set of vehicles that travel through a network with capacity restrictions and need to reach a destination at a fixed time. The vehicles incur a penalty for both any queuing delays and arriving at the destination early or late. In particular, we consider the case of a congested off-ramp, which is a common occurrence next to commercial hubs during the morning commute, and has the added negative effect of reducing the capacity on the freeway for through traffic. We study the use of incentives and tolls to manipulate the equilibrium...

The number and heterogeneity of traffic sensors are steadily increasing. A large part of the emerging sensors are measuring point speeds or travel times and in order to make efficient use of this data, it is important to develop methods and frameworks for fusion of point speed and travel time measurements in real-time. The proposed method combines a macroscopic traffic model and a non-linear filter with a new measurement model for fusion of travel time observations in a system that uses the velocity of cells in the network as state vector. The method aims to improve the fusion efficiency,...

Traffic performance metrics such as delay and Level Of Service (LOS), which are well documented in the Highway Capacity Manual (HCM), have been widely used by most of the transportation consulting companies, public agencies, and etc. For arterial delay analysis, prevailing commercial tools like Synchro have adopted the method proposed by the HCM, which is rooted in the Webster’s delay calculation proposed more than 50 years ago. The LOS is obtained using a lookup table that assigns a certain grade (from A to F) to the estimated delay according to its value. Without knowing detailed...