ITSLibrary's blog

This week’s Friday TRANSOC Seminar has Vikash Gayah, Ph.D. candidate, University of California, Berkeley, presenting “The Aggregate Effect of Turns on Urban Traffic Networks.” 

This research creates and uses macroscopic traffic models to describe the aggregate behavior of vehicles on urban street networks. Insights gained from these models can then be used to design network-wide policies that may increase the ability of these networks to serve vehicle-trips. In particular, this work focuses on the turning maneuvers that exist in networks with multiple routes. The presence of multiple routes and turning maneuvers are found to have two effects on aggregate vehicle behavior: 1) they cause unstable and inefficient behavior when a network is congested; and, 2) they may reduce maximum vehicle flows across the network. Fortunately, this work finds that limiting the rate at which vehicles are allowed to enter a network and providing drivers with real-time information on current traffic conditions can help mitigate the first effect and allow the network to operate more efficiently. It is also found that the second effect may not always be harmful—lower network flows do not necessarily result in decreased network efficiency if the lower flows are accompanied by more direct vehicle routing. In fact, two-way networks, which accommodate conflicting left-turns and result in lower maximum vehicle flows than one-way networks, are found to serve trips at a higher rate because drivers travel shorter distances on average. Thus, in many cities, maximum network efficiency can be improved by converting one-way streets to two-way operation.

The seminar will take place at 4:00 PM in534 Davis Hall. Please join us for a TRANSOC-sponsored Cookie Hour in the ITS Library at 3:30 PM.

This week's Friday TRANSOC Seminar has Lily Elefteriadou, Professor and Director of the Transportation Research Center, School for Sustainable Infrastructure and the Environment, University of Florida, presenting “Driver Behavior and Characteristics and Their Use in Traffic Modeling.” 

Traffic modeling has frequently considered and accounted for variability in driver behavior and characteristics.  For example, microscopic traffic simulators have the capability to replicate vehicular movements (such as lane changing) considering driver characteristics to a significant level of detail.  Such traffic simulators can typically replicate traffic streams with several different driver types which are based on driver aggressiveness.  Vehicular movements (such as car following) are then determined based on the respective action of the particular driver type.  However, a limited amount of research has been reported to categorize driver types or to link particular driving actions with a set of driver types and their characteristics.  Car-following, lane changing, and gap acceptance algorithms have rarely been calibrated to match various driver types, and it is not always clear how micro-simulators incorporate driver behavior aspects into these algorithms.  This presentation will describe two approaches to collecting driver behavior and characteristics-related data so that they can be used to improve traffic micro-simulators.  The first approach is based on focus groups, while the second is based on in-vehicle field data collection with an instrumented vehicle.  The presentation will describe these two data collection approaches and will provide three example applications related to freeway merging, car-following, and arterial lane changing. 

This week's Friday TRANSOC Seminar has Elizabeth Deakin, JD, Professor, City and Regional Planning and Urban Design, University of California, Berkeley, presenting "BART State of Good Repair: What It Will Take to Maintain the System."

The Bay Area Rapid Transit (BART) system is approaching 40 years of service, and BART is preparing for a large reinvestment program, including replacing overage vehicles and aging infrastructure to keep BART in a state of good repair (SGR).  However, some of the funding for this program is uncertain and therefore it is possible that some of the planned investment in the replacement of equipment and infrastructure will have to be deferred.  This presentation examines the levels and types of investment needed to maintain BART in a state of good repair, identifies the kinds of deterioration in BART services that are likely if less money is available for SGR than needed, evaluates how service deterioration would affect BART ridership, and assesses the consequences for the Bay Area’s transportation system, the economy, and the environment.  Stakeholder perspectives on funding for SGR also are investigated.

This week’s Friday TRANSOC Seminar has Tasos Kouvelas, Ph.D., Postdoctoral Researcher, University of California, Berkeley, presenting  “Adaptive Fine-tuning for Large-scale Nonlinear Traffic Control Systems.”

This talk introduces and analyzes a new learning/adaptive algorithm that enables automatic fine-tuning of Large-scale Nonlinear Traffic Control Systems (LNTCS), so as to reach the maximum performance that is achievable with the utilized control strategy. LNTCS have many applications in transportation, as with urban signal control or ramp metering, and yet their efficient design and deployment remains elusive due to the involved complexity and nonlinearities. Often, the deployment of a new algorithm (or the updating of an existing one) requires extensive fine-tuning before it reaches its best achievable performance. Typically, this fine-tuning procedure is conducted manually, via trial-and-error, relying on expertise and human judgment and without the use of a systematic approach. The proposed Adaptive Fine Tuning (AFT) algorithm is aiming at replacing the conventional manual optimization practice with a fully automated online procedure. The talk provides a detailed analysis of the algorithm as well as a step-by-step application description. Finally, application results of the algorithm to real-time fine-tuning problems of general LNTCS are presented using the commercial micro-simulation tool AIMSUN.

The seminar will take place today 4:00 PM in 406 Davis Hall. Please join us for a TRANSOC-sponsored Cookie Hour in the ITS Library at 3:30 PM.

This week’s Friday Seminar has Sebastien Blandin, PhD., Research Scientist, IBM Singapore Research Collaboratory, presenting “Modeling, Estimation and Control of Distributed Parameter Systems: Application to Transportation Networks.”

Scalar conservation laws expressing the evolution of traffic density have been extensively used for macroscopic traffic modeling and forward simulation using loop detector measurements. The mobile sensing paradigm allowing increased understanding of traffic flow motivates the need for novel partial differential equation results, of practical interest for real-time traffic operations. The research contributions of this work are centered on traffic modeling capabilities, data assimilation performances, and Lyapunov stabilizability guarantees. We propose a new 2X2 phase transition model of traffic flow able to account for classical traffic phenomena as well as heterogeneous driving behaviors. In the context of traffic information systems and filtering algorithms, we present one of the first numerical and analytical descriptions of the consequences of the emergence and propagation of shockwaves in traffic flow on estimates accuracy. Finally, we propose a Lyapunov stability result for the entropy solution to the transport equation using boundary actuation. The results presented in this work are instantiated on the Mobile Millennium system providing real-time traffic estimates in Northern California.

The seminar will take place on Friday, January 27, from 4:00-5:00 p.m. in 534 Davis Hall.

Today’s TRANSOC Friday Seminar has Nikolas Geroliminis, PhD., Assistant Professor, Urban Transport Systems Laboratory, École Polytechnique Fédérale de Lausanne (EPFL) presenting “The M6 of traffic systems: Macroscopic Modeling, Monitoring and Management of Multimodal Mobility.”

As more people and transport modes compete for limited urban space to travel, there is a need to understand how this space is used for transportation and how it can be managed to avoid traffic congestion. Our research seeks to shed some light in the modeling, planning and management of traffic flow for overcrowded cities with multimodal transport. We develop methodologies to model and understand the collective behavior for different types of multi‐modal systems, with emphasis in conflicts for the same road space (e.g. mixed traffic of buses and cars). The goal is to develop optimization tools on how to distribute city road space to multiple modes and to understand the level of accessibility for cities of different structures. We also investigate what type of real-time active traffic management schemes (congestion pricing, vehicle restriction, large scale traffic signal control) can improve mobility measures in a city. Until now traffic control systems in urban areas are locally programmed with little control over the impact of a micro-scale response to the macro-scale level. We build a hierarchical feedback control network of multiple levels. The validation of the modeling methodologies and the traffic management schemes are conducted in various and complex city structures scenarios using data from field experiments advanced micro-simulations.

The seminar will take place today 4:00 PM in 406 Davis Hall. Please join us for a TRANSOC-sponsored Cookie Hour in the ITS Library at 3:30 PM.

Red light cameras and other forms of automated traffic law enforcement continue to generate controversy. This week, Iowa Governor Terry Branstad said that he is in favor of banning such devices and a bill was introduced in the Colorado legislature to ban photo enforcement. On the other hand, the Insurance Institute for Highway Safety found strong public support for camera enforcement in cities with such programs. Much of the debate in Iowa and elsewhere stems from disagreement over whether such enforcement enhances traffic safety or merely produces revenue in the form of fines. Privacy is also a big concern and some who object on these grounds also see a very disturbing trend towards privatization of law enforcement. US PIRG released a report in October which outlines some of the pitfalls in privatization, including conflicts of interest, political clout of vendors and possible intrusion in setting transportation policy.

In today's New York Times, architecture critic Micahel Kimmelman looks at parking requirements for urabn development and he doesn't like how things have been going. 

For big cities like New York it is high time to abandon outmoded zoning codes from the auto-boom days requiring specific ratios of parking spaces per housing unit, or per square foot of retail space. These rules about minimum parking spaces have driven up the costs of apartments for developers and residents, damaged the environment, diverted money that could have gone to mass transit and created a government-mandated cityscape that’s largely unused. We keep adding to the glut of parking lots. Crain’s recently reported on the largely empty garages at new buildings like Avalon Fort Greene, a 42-story luxury tower near downtown Brooklyn, and 80 DeKalb Avenue, up the block, both well occupied, both of which built hundreds of parking spaces to woo tenants. Garages near Yankee Stadium, built over the objections of Bronx neighbors appalled at losing parkland for yet more parking lots, turn out never to be more than 60 percent full, even on game days. The city has lost public space, the developers have lost a fortune.

Streetsblog wonders what this endorsement for eliminating parking minimums might have on the Department of City Planning. 

This is not a new topic by any means. Donald Shoup's High Cost of Free Parking is a cornerstone of the field. Researchers from NYU have looked at the enforcement of New York City's minumum parking requirements and how proximity to transit affects the reuirements and the impact on housing affordability. There is also a thought that well-functioning off-street parking markets might be a solution. 

This week's Guadian Focus Podcast discusses whether or not Boris Johnson's cycling superhighways have really improved cycling for the London area, in light of yet another cycling death. A study from 2010 questions shows that fatality rates did not drop between 1992-2006. Here's a map of cycling accidents in London between 2000 and 2008. Despite Johnson's proclamation fo 2010 being "London's year of cycling," ultimately cycling success will depend on public safety.