Volvo Center

Clockwise Hysteresis Loops in the Macroscopic Fundamental Diagram

Gayah, Vikash V.
Carlos Daganzo
2010

A recent study reported that the Macroscopic Fundamental Diagram of a medium size city exhibited a clockwise hysteresis loop on a day in which a major disturbance caused many drivers to switch to unfamiliar routes. This paper shows that clockwise loops are to be expected when there are disturbances, especially if the disturbances cause a significant fraction of the drivers to not change routes adaptively. It is shown that when drivers are not adaptive networks are inherently more unstable as they recover from congestion than as they are loaded. In other words, during recovery congestion...

Modular Composition of Synchronous Programs: Applications to Traffic Signal Control

Zennaro, Marco
Raja Sengupta
2006

This paper describes a modular compilation scheme for distributed synchronous programming. The approach is first described mathematically and then implemented as a library to distribute Simulink (59). Application of the scheme is illustrated by developing a control system to coordinate traffic signals.

CHAL - Control logic / Hardware Abstraction layer

Zennaro, Marco
Raja Sengupta
2007

Traffic control systems have reached a high level of sophistication: they are general purpose machines that can, in principle, run any traffic control software. The firmware they are running turns them into special purpose machines able to operate only according to some pre-defined rules. The firmware usually allows limited customizations through parameters, but it does not support the introduction of new control schemes. As a result, implementing a new traffic control scheme requires the re-implementation of the firmware, a complex task given the low-level programming required. The...

Innovative Bus-Lane Deployments in Amman: Proposed Field Experiments

Guler, Ilgin
Michael Cassidy
2010

Innovative strategies for deploying bus lanes are proposed for field tests in Amman, Jordan. The objective is to reduce delays to buses in the network while minimizing delays to other vehicular traffic. The proposed strategies may be far better options than conventional, static bus lanes, given the test site’s large car demand and low bus frequency. The experiment is designed to be conducted in simple, safe ways, without the need for investment in permanent infrastructure.

Dual Influences on Vehicle Speeds in Special-Use Lanes and Policy Implications

Jang, Kitae
Michael Cassidy
2011

Slow speeds in a special-use lane, such as a carpool (HOV) or bus lane, can be due to both high demand for that lane and slow speeds in the adjacent regular-use lane. These dual influences are confirmed from months of data collected from all freeway carpool facilities in the San Francisco Bay Area. Both influences hold for other types of special-use lanes, including bus lanes. New US regulation stipulating that most classes of low-emitting vehicles, or LEVs, be banned from slow-moving carpool lanes. While LEVs invariably constitute only about 1 percent of the freeway traffic demand in the...

Unintended Environmental Impacts of Nighttime Freight Logistics Activities

Sathaye, Nakul
Harley, Robert
Madanat, Samer
2009

In recent years, the reduction of freight vehicle trips during peak hours has been a common policy goal. To this end, policies have been implemented to shift logistics operations to nighttime hours. The purpose of such policies has generally been to mitigate congestion and environmental impacts. However, the atmospheric boundary layer is generally more stable during the night than the day. Consequently, shifting logistics operations to the night may increase 24‐hour average concentrations of diesel exhaust pollutants in many locations. This paper presents realistic scenarios for two...

Urban Densities and Transit: A Multi-Dimensional Perspective

Cervero, Robert
Guerra, Erick
2011

This paper investigates the relationship between transit and urban densities in the United States. An analysis of light rail systems finds that a residential density of about 30 people per gross acre near stations is needed to in order to make them among the top 25 percent of rail transit investments in terms of cost effectiveness; for heavy rail systems, the density is 45 people per gross acre. Increasing density around stations would greatly increase ridership, particularly when jobs are located within one-quarter mile of the stations and housing is located within one-half mile....

Rail + Property Development: A Model of Sustainable Transit Finance and Urbanism

Cervero, Robert
Murakami, Jin
2008

Hong Kong has aggressively pursued transit value capture to finance railway infrastructure through its “Rail + Property” development program, or R+P. More than half of all revenues received by the MTR Corporation, the owner-operator of Hong Kong’s largest railway network, come from property development. A wide variety of R+P projects presently exist in Hong Kong. Most focus on housing development though all have some degree of commercial development. Recent generation R+P projects have placed a stronger premium on urban design and quality of pedestrian environments. This has generally paid...

Use Characteristics and Mode Choice Behavior of Electric Bikes in China

Cherry, Chris
Cervero, Robert
2006

In 2005, ten million electric bikes were produced in China. Strong domestic sales are projected for coming years, raising concerns about the sustainability and potential regulation of this fairly new mode. Policy makers are wrestling with development policy on electric bikes with little information about who uses them, why they are used, and what factoes influence the electric bike travel. This paper probes these questions by surveying electric bike usage in two large Chinese cities, Kunming and Shanghai. Demographic comparisons are made between the different modes and cities as well as...

Advancing Bus Rapid Transit and Transit Oriented Corridorsin California’s Central Valley

Braughton, Matthew
Brill, Matthew
Lee, Stephen
Binger, Gary
Cervero, Robert
2011

This study explores possibilities for advancing bus rapid transit (BRT) systems and associated higher density land development in the Central Valley of California. It uses photo-simulations and stakeholder reactions to visual images to gauge public attitudes toward what would be a fairly radical transformation of urban environments in traditionally car-oriented settings.The kinds of transformations that would be needed to economically justify higher quality BRT services will likely require better and more frequent bus as well as amenities in the form of street trees, landscaping, street...