Cross-cutting Issues

SRA (The Swedish Road Administration) has since 2002 used Bridge-WIM systems. The
result has so far indicated a widespread overloading. The information is also important for
planning of road maintenance. Weight monitoring has thus provided SRA with vital
information. SRA has decided on an action plan to address the problem with overloading. The
action plan will generate new ITS-solutions and continued weight monitoring in Sweden. One
example is on board weight control on Heavy Goods Vehicles (HGV). This could have a
greater impact if there are a European and international co-operation and harmonisation on
electronic vehicle identification and remote declaration of vehicle characteristics. Overloading
is a cross border problem. On the next ITS World Congress in Stockholm 2009 we intend to
show different aspects on the concept “a correctly loaded vehicle”.

Swedish Road Administration

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

In this paper, improving DS/SS inter-vehicle communication using p-persistent
CSMA MAC protocol is studied. It is possible for p-persistent CSMA to adapt optimally to
current packet traffic situation by setting p to an appropriate value. Therefore, improvement of
IVC performance is expected if optimal p value can be set according to the traffic of vehicles.
In order to perform this, the scheme where the traffic monitor on the road side informs the
appropriate p value to each vehicle in the area using road-vehicle communication is proposed
and its performance is analyzed by simulations.

Tokyo University of Science

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

Floating car information systems (probe car information systems) are currently
being implemented. As a critical service, estimated link travel times are obtained from
collected link travel times for utilization in vehicle navigation systems. Such estimated link
travel times must be appropriate for the situations arising during navigation, since they are
affected by various factors, including time period, traffic volume, and weather. However, the
actual system does not consider the effect of weather for link travel time estimation. Besides,
it does not make an evaluation of the floating car data actually available. Furthermore, no
in-depth evaluation is made regarding the minimum amount of data necessary for estimation
of link travel time. This paper uses data actually obtained by floating car systems, and takes
into account the effect of weather (e.g., snowfall) for an estimation of link travel time, thereby
revealing the effect of weather differences on estimated link travel time. In addition, it
evaluates the amount of data required to obtain estimated link travel time, as well as estimated
values, while maintaining accuracy, thereby revealing the characteristics of such data from
various actual data.

Honda Motor Co.

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

The aim of this study is to report on the development of the evaluation method using the travel time reliability and case studies for the particular transportation projects on Tokyo Metropolitan Expressway (MEX), including traffic safety measures and new routes. Each project may contribute to safer and smoother traffic, but most projects were assessed by different methods. It is difficult to assess various projects using the unified measurement. In this paper, the Buffer Time Index (BTI) and the statistics of travel time were used for the evaluation of travel time reliability, and those were applied to the actual transportation projects on MEX. Then, new reliability indexes which are suitable for analyses of various projects are proposed. Using these indexes, the effects of both the safety projects and the construction projects can be assessed. These assessments were allowed by plentiful traffic data, which were collected by vehicle detectors with an approximately 300m interval on MEX.

Metropolitan Expressway Company Limited

Pacific Consultants Company Limited

Institute of Industrial Science, the University of Tokyo

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

A common method of Dilemma zone (DZ) protection at isolated intersections is to hold the green until the number of vehicles in DZ is lower than a threshold number. Since the threshold number is empirical and fixed, it cannot accommodate the dynamic and time-varying traffic patterns and therefore have to be adjusted regularly. This paper presents a new Markov-process-based DZ protection algorithm, which considers the number of vehicles in DZ (state) as a Markov process. At each time step, the algorithm first predicts the future states with the Markov state-transit matrix then compare them with the current state to determine whether to end the green or not. As a result, the new end-green criterion is determined not by the fixed threshold values but by the current state and the Markov state-transit matrix. Meanwhile, the Markov matrix is automatically updated when the new observed detected state transitions come in. The simulation results showed that the new algorithm maintains reliable and effective protection in a dynamic traffic environment. At last, we present an evaluation of the new algorithm performance using two methods of calculating the current state: low-fidelity prediction with advance detectors and high-fidelity prediction with future Connected Vehicles Technologies.

Authors: Pengfei Li Ph.D., Montasir M. Abbas, Ph.D., P.E., Raghu Pasupathy, Ph.D.

Presented at the 18th World Congress on ITS, October 2011, Orlando, Florida