Safety

The overall objective of the study is to understand the occurrence of
primary and secondary incidents and relevant incident management strategies, as
well as to understand how primary incident duration and secondary incident
occurrence are related. Specifically, secondary incidents are more likely to occur
if the primary incident lasts long; at the same time, the durations of primary
incidents are expected to be longer if secondary incidents occur. The work will
allow State Departments of Transportation to estimate the chances of a secondary
incident based on the characteristics of the primary incident, evaluate associated
delays, and aid in identifying incident management strategies to mitigate the
impacts of both primary and secondary incidents. Freeway incident and roadway
inventory data from the Hampton Roads area in Virginia were used in this study.
Modeling and simulation techniques were applied to develop primary incident
duration and secondary incident occurrence/duration prediction models. Models
for primary incident durations and whether or not a secondary incident occurs are
estimated. The interdependence is modeled by using the incident duration as
endogenous variable in secondary incident occurrence models. The results show
statistical evidence for interdependence, but when it is taken into account, no
substantial differences in the magnitudes and statistical significance for the
estimated independent variables are found (compared to when the
interdependence is not accounted for). Statistically significant correlations are
found between secondary incident occurrence and other variables, allowing us to
recommend aggressive incident clearance procedures on qualifying high-volume
roadways to avoid secondary incidents.

Old Dominion University

Presented at the 15th World Congress on Intelligent Transport Systems, November 16-20, 2008, New York, New York

This  paper  proposes  a  real-time  adaptive  control  model  for  signalized  intersections  that
decides optimal control parameters commonly found in modern actuated controllers, aiming
to exploit the adaptive functionality of traffic-actuated control and to improve the performance
of  traffic-actuated  signal  system.  This  model  incorporates  a  flow  prediction  process  that
estimates the future arrival rates and turning proportions at target intersections based on the
available signal timing plan and detector information. Signal control parameters are optimized
dynamically cycle-by-cycle to satisfy these estimated demands. The proposed adaptive control
strategy is tested on a network consisting of thirty-eight actuated signals using microscopic
simulation. Simulation results show that the proposed adaptive model is able to improve the
performance of the study network, especially under off-peak traffic conditions.

University of California, Irvine

University of California, Berkeley

Presented at the 15th World Congress on Intelligent Transport Systems, November 16-20, 2008, New York, New York

We describe a computational architecture of a collision early warning system for ve-
hicles and other principals. Early warnings allow drivers to make good judgments and
to avoid emergency stopping or dangerous maneuvering. With many principals (vehicles,
pedestrians, bicyclists, etc) coexisting in a dense intersection, it is difficult to predict even
a few seconds in advance, since there are an enormous number of possible scenarios. It is a
major challenge to manage computational resources and human resources so that only the
more plausible collisions are tracked and of those, only the most critical collisions prompt
warnings to drivers. In this paper, we propose a two-stage collision risk assessment process,
including (1) a preliminary assessment via simple efficient geometric computations which
throughly considers surrounding principals and identifies likely potential accidents, and (2)
a specialized assessment which computes more accurate collision probabilities via sophis-
ticated statistical inference. The whole process delivers an expected utility assessment to
available user-interfaces, allowing the user interfaces make discriminating choices of when
to warn drivers or other principals.

Palo Alto Research Center

Fujitsu Limited

Presented at the 15th World Congress on Intelligent Transport Systems, November 16-20, 2008, New York, New York

Middleware has emerged as an important architectural component in supporting distributed
applications. The role of middleware is to present a unified programming model to
application writers and to mask out problems of heterogeneity and distribution. This paper is
motivated by the convergence of the embedded sensor and mobile communication
revolutions in the automobile. The national vehicle fleet is morphing into a vast mobile
sensor fleet. In this paper, we provide a middleware architecture and implementation that
addresses the needs of a distributed system of mobile sensors comprised of vehicles and
intersections producing traffic related data for traffic safety and operations. We conclude our
paper with some performance measures that relate to the cost of overhead incurred from
using the middleware. The measurements show the middleware is efficient enough for certain
road safety and congestion relief applications.

University of California, Berkeley

Presented at the 15th World Congress on Intelligent Transport Systems, November 16-20, 2008, New York, New York