Transcript INTELLIGENT URBAN TRAFFIC SIGNALLING INFRASTRUCTURE WITH OPTIMIZED INTRINSIC SAFETY Prof. Marius MINEA, Ph.D Lect.

INTELLIGENT URBAN TRAFFIC
SIGNALLING INFRASTRUCTURE WITH
OPTIMIZED INTRINSIC SAFETY
Prof. Marius MINEA, Ph.D
Lect. F.C. Nemtanu, Ph.D. Stud.
POLITEHNICA University of Bucharest
ICCCC 2006 – Baile Felix Spa
Introduction
What is ITS? ITS stands for
“Intelligent Transport Systems”,
representing a set of measures
undertaken to improve information,
safety and seamless flow of
transport and traffic. ITS deals with
the term “Telematics”, a
combination of the technologies
involving Telecommunications and
Informatics
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Main ITS components
ATMS – Advanced Traffic Management
Systems;
ATIS – Advanced Traffic Information Systems;
CVO – Commercial Vehicles Operations;
APTS – Advanced Public Transport Systems;
AVCS – Advanced Vehicle Control Systems.
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UTMC Systems
An UTMC system, component of Intelligent
Transport Systems, defines a generalised
architecture for traffic management and vehicles
priority in terms of:
Monitoring/location of Public Transport Vehicles
(PTVs), or other type of vehicles;
Road Network Modelling;
Traffic Management Strategy Selection;
Strategy Implementation;
Management of common/historic databases.
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Adaptive signal control has recently
emerged as a viable system control
strategy within the United States, Europe
and Australia. Long used in Europe and
Australia, adaptive control consists of the
real-time adjustment of coordinated signal
timing parameters as well as independent
intersection control to adapt to changing
traffic conditions.
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Benefits of ITS
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Safety improvement – a major goal of ITS
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Specific, existing UTMC systems
Specific UTMC systems, such as SCOOT,
SCATS, UTOPIA, SITRAFFIC, ITACA are
now wide spread around the world and
already considered “mature” UTMC
systems.
SCOOT – Split Cycle Offset Optimization Technique
SCATS - Sydney Coordinated Adaptive Traffic System
UTOPIA - Urban Traffic Optimisation by Integrated Automation
SITRAFFIC – Siemens Intelligent TRAFFIC system
ITACA – Intelligent Traffic Adaptive Control Agent
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Using Mathematic Algorithms for
Traffic Modeling
Several Traffic models:
– Static models – using fixed traffic data,
allocated to Origin-Destination matrixes;
– Dynamic models – using variable data for
traffic flows between nodes of a matrix;
– Continuous models – using fluids laws for
modeling traffic behavior;
– Micromodelling – using time division to
describe local traffic behavior;
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Specific diagrams – traffic demand
in a city
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Specific diagrams
Vehicles speed (q) versus traffic density (k)
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Simplifying the process, the UTMC system
measures continuously traffic demand using
special detectors. Then, it calculates optimal
signaling using several techniques, according to
the technology and software.
For example, the traffic models that use fluids
flowing laws are represented by a set of
mathematical equations; some of these can be
solved analytically, some with numerical
procedures. In practice, a link between two
junctions is divided in several “cells” with a
length equivalent to a normal vehicle. Traffic
conditions are estimated using time splits of 0.5
to 10 seconds. Information is then distributed to
traffic controllers, that actuate traffic lights.
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Characteristic
entities
Static models
Dynamic
models
Continuous
models
Microsimulation
Traffic
volumes
AR
AP
N
N or AR
Speed
AR
AR
AP
AP
Speed
distribution
N
AR
AR
AP
Accelerations
N
N
AR
AP
Influences in
traffic
volumes
N or AR
N or AR
N or AR
AR
Legend: A – Available feature; N – non-available; R – reduced
accuracy; P – precision of the models
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Logical diagram for the Following
Vehicle Pattern Model (example)
ERRORS
“IN FRONT”
VEHICLE STATUS
VEHICLE DRIVER
PERCEPTIONI
NFORMATION
COLLECTION
DECISION
EXECUTION
FEEDBACK REACTION
VEHICLE
DYNAMICS
NEXT VEHICLE STATUS
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Present state in Romania
There are no important UTMC systems implemented (exceptions
are the UTOPIA for 41 “Light metro” line in Bucharest, and the future
Bucharest Multisector UTC/PTM/CCTV project for around 100
junctions and 300 buses);
The signalling infrastructure is heterogeneous, obsolete and
frequent failures are reported;
There is no a centralised concept in monitoring, control and repair
operations for the road signalling infrastructure;
There is no an updated database concerning the field facilities kept
at an administrative authority (such as Street Administration) – so as
at this moment, if a traffic signal or sign is damaged or missing,
there will be a big delay (days) until the authority will be noticed and
maintenance will be performed;
The Street Administration required several times a centralised,
integrated method/platform for field data acquisition/monitoring of
the signalling infrastructure.
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Designing an ITS platform for the
road signalling infrastructure
SIGNALLING
ELEMENTS
POSITIONS DATA
COLLECTION
Human Operators
AUTOMATIC FAULT
REPORTING
Traffic controllers
Traffic
controllers
Radio or wired data network
OPERATION AND
MAINTENANCE
CENTRE
Maintenance Companies
and Operators
USERS INFORMATION
Traffic participants
Road users
SYSTEM
Media and information
distribution centre
Functional architecture for the Optimised Signalling Infrastructure
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Specific requirements for the integrated
optimised signalling infrastructure
Traffic management systems by definition
contain functions for the detection and selection
of vehicles and functions associated with the
granting of priority;
A very important characteristic of the
communications network for these systems is
that the delay for any operational data must be
strictly controlled;
The communications network is a crucial
element in an optimised signalling infrastructure.
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Specific architectures for priority
granting and fault management functions
When the priority strategy is separate and
interrupts the background strategy, then there is
scope for a variety of architectures. It is possible,
but not necessarily desirable for some or all of
the priority functions to be logically separated
from the background control function. Four
groups of architectures are possible:
– Centralised UTC and priority functions, centralised fault
reporting;
– Decentralised UTC and priority functions, centralised fault
reporting;
– Centralised UTC with decentralised priority functions,
centralised fault reporting;
– Decentralised UTC with centralised priority functions,
centralised fault reporting.
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Fault reporting
As seen in the above classification,
the fault reporting / management
function should be always centralised,
as this is very important for the good
operational status of the system. In all
cases, even if there is or there is not a
wired communication network link to a
management centre, there is a must
to have a radio link (or GSM network
link) for the fault monitoring function.
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Specific architectures (1)
Centralized control, all functions
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Specific architectures (2)
Decentralized control, all functions
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It is a known fact that the road
transportation is most affected with traffic
incidents, casualties, traffic jams and
general congestion, due to the large
number of vehicles, both private and/or
belonging to state agencies or companies.
Implementing ITS in urban transport
means introducing mathematic algorithms
for traffic optimization, introducing
“intelligence” at the street level.
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Conclusions
Traffic management systems are complex
architectures, with core processing
equipment that requires sensor data
fusion, mathematic algorithms and good
communications infrastructure;
Increasing the intrinsic reliability thru
specific measures means reducing traffic
incidents, environmental pollution and
costs for transport.
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Thank you!
www.e-safety.ro
www.eltrans.pub.ro
UPB-CEPETET
Centrul de Cercetare, Proiectare, Service si Consulting in
domeniul Telecomenzilor si Electronicii in Transporturi
[email protected]
[email protected]
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