Roads/Highways

The Spatial Evolution of Traffic Under the Two Wave Speed Assumption: A Shortcut Procedure and Some Observations

Daganzo, Carlos F.
1993

This paper describes the behavior of traffic in a homogeneous highway according to the hydrodynamic theory, in the special casewhere the flow-density relationship is triangular; i.e. when only two wave velocities exist. It presents an exact formula thatpredicts the vehicle that would be found at position x at time t, given the locations of all the vehicles at time zero. The formula, which does not require identification of the vehicle positions at intermediate times, automatically accounts for the creation and dissipation of any shocks. It can be used to calculate system performance...

DYN-OPT Users Manual

Caliskan, C.
Hall, R.W.
1997

This document is a users manual for DYN-OPT, a linear program that optimally and dynamically assigns traffic to lanes on an automated highway. The program maximizes the total flow across the highway over a pre-specified length of time. DYN-OPT solves a path-based formulation in which the highway is represented by discrete segments, time is divided into periods and traffic between origins and destinations follows a user- specified distribution.

A Cooperative V2V Alert System to Mitigate Vehicular Traffic Shock Waves

Vince Rabsatt, Reuben
Gerla, Mario
2018

We address the problem of shockwave formation in uncoordinated highway traffic. The problem is caused by the combination of heavy traffic and small traffic perturbations or unexpected drivers actions. We propose a novel distributed communication protocol that helps mitigate upstream shockwave formation even with extremely low system penetration rates. Based on traffic information ahead, the Cooperative Advanced Driver Assistance System (CADAS) recommends non-intuitive velocity reductions in order to redistribute traffic more uniformly and eliminate traffic peaks. Simulation results show...

From LOS to VMT, VHT and Beyond Through Data Fusion: Application to Integrate Corridor Management

Bayen, Alexandre
Gan, Qijian
Gomes, Gabriel
2016

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...

Mapping and Improving the Delivery Process of Highway Pavement Rehabilitation Projects

Tommelein, Iris D.
Blampied, Nigel
2018

Highway pavement rehabilitation (HPR) is a service provided by departments of transportation (DOTs) worldwide. The process of delivering HPR projects involves not only a transportation department but also many other project participants and stakeholders; furthermore, it is subject to numerous technical- as well as socio-political considerations. Interestingly—though not surprisingly—the processes DOTs use to deliver this service vary widely, not only between countries or between states in the US, but also regionally within a given state such as California. While some variation is to be...

Control Strategies for Corridor Management

Amiri, Zahra
Lo, Yu-Chieh
Skabardonis, Alexander
Varaiya, Pravin
2016

Integrated management of travel corridors comprising of freeways and adjacent arterial streets can potentially improve the performance of the highway facilities. However, several research gaps exist in data collection and performance measurement, analysis tools and control strategies. In this project first we analyzed high resolution data consisting of time-stamped records of every event involving vehicles, together with the signal phase at real-world signalized intersections and developed procedures for estimating performance measures. Next, we assessed the performance of a new...

Calculating and Forecasting Induced Vehicle-Miles of Travel Resulting from Highway Projects: Findings and Recommendations from an Expert Panel

Deakin, Elizabeth
Dock, Fred
Garry, Gordon
Handy, Susan
McNally, Michael
Sall, Elizabeth
Skabardonis, Alex
Walker, Joan
Rheinhardt, Karl
2020

In the context of implementation of SB 743 (Steinberg, 2013), staff at the California Department of Transportation (Caltrans) have been developing guidance documents on how to calculate induced travel, working with their counterparts at the California Air Resources Board (CARB) and the Governor’s Office of Planning and Research (OPR). OPR’s technical advisory discusses two methods for estimating induced travel: an approach based on the application of travel models and an approach using elasticities drawn from the peer-reviewed literature (such as the National Center for Sustainable...

Historical Transportation Development

Garrison, William L.
2003

The main tasks for this overview of transportation development are the provision and interpretation of information on the unfolding of the transportation systems. What have been the processes at work? What explains the similarities and differences from here to there and among systems? Big questions! But they are eased by ways systems are products of experiences, as will be seen when the paragraphs immediately following summarize early experiences. Life support systems, sustainability, and social development topics will be mentioned. After examining their immediate precursors, the...

Some Observations Of Highway Traffic In Long Queues

Smilowitz, Karen
Daganzo, Carlos
Cassidy, Michael
Bertini, Robert
1998

The arrival times of vehicles traveling southbound along a two-lane, bi-directional highway were recorded at eight neighboring locations upstream of a bottleneck caused by an oversaturated traffic signal. Cumulative curves constructed from these observations describe completely and in great detail the evolution of the resulting long queues. These queues formed directly upstream of the signal when the signal's service rate fell below the southbound arrival rates, and never formed away from the bottleneck. The predictability of bottlenecks like the one studied here can be exploited to manage...

System Optimum Diversion of Congested Freeway Traffic

Laval, Jorge A.
Munoz, Juan Carlos
2002

We study the system optimum dynamic traffic assignment (SODTA) in a network consisting of a freeway and neighboring city streets. There is only one bottleneck in the freeway and every destination is somewhere downstream of the bottleneck. Vehicles can be diverted through off-ramps leading to alternative local street routes. We formulate the problem and determine a graphical solution procedure based on Newell's cumulative plots, which yields the optimal diverted flow over time. On-ramps can be conveniently incorporated in this procedure yielding SO metering rates. The following variants are...