Event Type: Seminar

What are the prospects for economic development in lagging sub-national
regions? What are the roles of public infrastructure investments and fiscal
incentives in influencing the location and performance of industrial activity?
To examine these issues, I estimate a spatial probit function for industrial
activity in Brazil that explicitly incorporates infrastructure and fiscal
improvements in the cost structure of individual firms. Using firm-level data
from a 2001 annual industrial survey and regional/ spatial data at the micro-
regional level, I find considerable firm-level cost savings from location in
areas with relatively lower transportation costs to large markets. In
comparison, fiscal incentives have modest effects on firm-level costs.
Although this suggests that firms benefit from locations with good access to
markets, it does not necessarily suggest that improving inter-regional
connectivity will help lagging regions. Improving inter-regional connectivity
implicitly reduces a natural tariff barrier so firms that currently serve large
markets and benefit from economies of scale can more easily expand into
new markets in competition with local producers. Thus, producers in the
leading regions can crowd out local producers, with detrimental effects on
production and employment in the lagging region.

Advances in wireless technologies have stimulated interest in the use of inter-vehicle communication as the foundation of decentralized advanced transportation information systems. In this seminar, I discuss the reliability of inter-vehicle communication in a traffic stream, dependent on the distribution of equipped vehicles. Assuming that information propagation is instantaneous compared to vehicle movements, I measure reliability as the probability of success that information will travel beyond a specified location. I present stochastic models for both uniform and general traffic streams. In the models, I divide the traffic stream into a series of cells based on the transmission range, clarify the structure of possible most-forward-within-range communication chains, regressively compute the probabilities for information to travel to and beyond a vehicle at a certain hop, and determine the lower bound of the absolute success rate for information to travel beyond a point. Based on the models, I examine the performance of information propagation for different penetration rates, transmission ranges and traffic scenarios that include gaps and shock waves. I conclude by discussing implications and extensions of this effort.

Daily traffic assignments on a large-scale road network are described for ‘build’ and
‘no-build’ scenarios to evaluate the addition of two proposed ramps between I-295
and SR-42 in the New Jersey part of the Delaware Valley Region. The road network
consists of 39,800 links connecting 1,510 zones. The user-equilibrium traffic
assignment problem was solved with a new algorithm called origin-based assignment
(OBA) that can achieve highly converged solutions with reasonable computing effort.
The stability of link flow differences between the two scenarios in the vicinity of the
proposed ramps are examined over a broad range of assignment convergence levels.
Then, link flow differences over this range of convergence levels are compared to link
flow differences between two very highly converged solutions. The findings reveal
that a relative gap of 0.01% (0.0001) is required to ensure that the traffic
assignments are sufficiently converged to achieve link flow stability. These
convergence levels are then interpreted in terms of the number of Frank-Wolfe
iterations and computational effort required to achieve comparable relative gaps.

Microscopic traffic simulators — tools that realistically emulate the flow of individual vehicles in a road network — provide a reliable means of testing and evaluating the anticipated benefits of large transportation investments. These tools can capture the full dynamics of time-dependent traffic phenomena and account for drivers’ reactions to ITS technologies and strategies. This seminar will introduce the main features of the AIMSUN microscopic traffic simulation system and illustrate its use in two recent projects: the design and testing of an adaptive tunnel traffic management system (the Saint Gothard tunnel in Switzerland) and the ISM advanced network-level traffic management system in Germany’s State of Hessen. These case studies address a new domain for traffic simulation: support of traffic management decisions. The seminar will conclude with a presentation and discussion of enhancements to the AIMSUN system specifically designed to support traffic management decision making.