french institute of science and technology for transport ... - Ifsttar

2_SCIENTIFIC AND TECHNICAL ACTIVITIES
Road traffic management
New techniques
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The requirements of sustainable mobility are prompting
road operators to test new road traffic management
techniques. A new multicriteria approach for evaluating
these, which is based on the level of service, was finalized
in 2011.
During the day, a road operates with four possible levels
of service: free flow, dense flow, capacity flow and saturated
flow. The level of service is linked not only to the physical
characteristics of the road and traffic demand, but also driving
Mean
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behaviours and the weather. The level of service concept can
be used to evaluate the impact of traffic management techniques
on congestion, the environment and safety. Variations
in the total time spent driving under saturated conditions characterizes
how a traffic management measure affects congestion.
Aggregating data on the basis of level of service is a more
precise way of computing pollution and fuel consumption than
the usual breakdown by mean vehicle speed bracket. Last,
the rate of injury accidents on a network is related to the
levels of service at the time. The methodology is undergoing
validation for a number of variable lane allocation operations
(for example the taxi lane on the A1 motorway). In addition,
a network operation strategy selection tool, which takes the
form of a catalogue of standard cases, is being developed. It
can be used for the Paris region network to make decisions
on the basis of the configuration of the infrastructure and the
level of congestion.
The new approach can be integrated within traffic simulation
tools in order to make a priori evaluations. It could also be used
in traffic management centres for a posteriori evaluations. In
addition, potential ways of improving the method have been
identified, enabling it to be extended to the whole range of
dynamic road traffic management operations.
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Level of service
Free flow Dense flow Capacity flow Saturated flow
@ CONTACT
simon.cohen@ifsttar.fr
Average annual accident rate per hour-kilometre
of operation at different levels of service.
Virtual reality driving
simulation
Road safety on a headset
A virtual
reality headset.
Driving simulators and test tracks, which are the two
methods most commonly used today for testing and
evaluating driving aid systems, are not completely
satisfactory. Moving base simulator tests only generate
sensorimotor feedback within a limited range, and test
tracks can, in the case of certain situations, be dangerous
for the driver.
As part of the PARTAGE project (ANR-VTT-09),
IFSTTAR is proposing a new test mode for driving assistance
that combines the advantages of simulators and real vehicles.
The difficulty was resolved by using a virtual reality headset
in a vehicle passenger compartment.
The vehicle positioning module uses the findings of the
European CVIS project (Cooperative Vehicle-Infrastructure
Systems) and the research carried out by Dominique Gruyer.
In view of the constraints with regard to the positioning and orientation
of the headset, the LIVIC unit developed a dedicated
module. This was necessary because all the systems on the
market have drawbacks in the context of this study: the need
for all metal parts and the target to be a certain distance away,
the need for lighting to be controlled and imperfect positioning
depending on whether the systems rely on the investigation of
the magnetic field, vision, inertia, or merging these.
Since September 2011, we have been working with OKTAL
(who are responsible for simulation and visual reproduction)
to evaluate the operation of the headset in a vehicle owned by
LIVIC. For this we have been using the Satory test track calibration
zone and car park. This area has been digitized and a
virtual zone has been constructed. This means the driver can
drive within this area while having the impression of being in
a residential area.
The initial results are conclusive. However, the positioning capabilities
of the headset will need to be extended to allow large
movements of the head.
@ CONTACT
sebastien.glaser@ifsttar.fr
ifsttar French Institute of Science and Technology for Transport, Development and Networks