| Tunnel Traffic Control Solution |
| Safety always comes first |
| Safety is always the central theme for tunnel control systems, since tunnels provide a vital link for major roads and highways. Tunnels present a hazard to motorists by the fact that they often constrict traffic flow, and are difficult to widen as the amount of traffic increases over time. Compared to open routes, incidents in tunnels can result in disastrous consequences. The restrictive nature of tunnels makes it extremely hard to remove wrecked or broken down vehicles, and rescue accident victims. Congestion and incidents such as breakdowns, fire, or exceeding carbon monoxide limits must be detected and dealt with in a timely manner. |
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| Description of Tunnel Control Systems |
| Tunnel control systems are managed from a centralized control room, and a comprehensive set of subsystems must be integrated into a consistent system for effective tunnel control. Comprehensive tunnel control subsystems consist of: |
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Tunnel power control: substations and uninterrupted power supplies |
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Traffic signal control (variable traffic signs using LED technology and traffic lights) |
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Automatic ventilation control and illumination |
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Emergency system and
broadcasting system |
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Height control system |
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Fire detection and protection system: acquiring fire detector data and control of the fire fighting system. Water accumulation and distribution are also included. |
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Pollution measurements: acquiring data on visibility and carbon monoxide concentration in the tunnel |
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Video monitoring system |
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| The Challenges |
| Today, tunnels handle large volumes of automobile traffic, sometimes moving at expressway speeds. In the narrow, confined environment of a tunnel, even minor incidents can cause deadly disasters, since critical, catastrophic incidents may occur even faster than on surface highways. Immediate response to traffic incidents is critical for maintaining a smooth traffic flow. For this reason, it must provide timely and vital information for operating personnel to advise motorists of the hazards in the tunnel. A second challenge is constant availability. Non-stop operation is a must to ensure maximum safety and reliability. |
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| Requirements |
| Since tunnels are considered
one of the most complex route sectors, safety, reliability,
and real-time access are key factors in constructing an
intelligent tunnel control infrastructure. A network that
connects and communicates all sub-systems must meet the
following requirements: |
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Ethernet-based Network Infrastructure |
| For tunnel control
systems, it is crucial to create an effective
network infrastructure to connect and communicate
with all sub-systems. In this day and age, IP
networks have many advantages over traditional
field buses.
In
addition
to supporting the transmission of any kind of data,
the other main advantage is the big increase in
data throughput. This enables extensive use of
video cameras in conjunction with the more common
control equipment, with all devices connected to
the same backbone ring through Industrial Ethernet
ring switches. |
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Redundancy & High Availability |
| Effective traffic management systems do not tolerate traffic downtime. As opposed to serial lines, Ethernet switches can be connected to a ring, with the ability of the system to detect a fiber or link failure and re-route data in the opposite direction. Such a process is very critical to ensure uninterrupted operation. The safety of motorists is ensured by the use of redundant Ethernet units. |
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Fast and Long Transmission |
| The network capacity should be sufficient to handle the large amount of data that is transmitted. Ethernet switches and fiber optic cabling offer fast and cost-effective bandwidth, and the reliability to relay all information from field controllers, sensors, and detectors. Standard Ethernet bandwidth includes 10, 100, 1000 Mbps, and fiber optic cabling offers high speed and secure connectivity over the long distances required in traffic applications, including bridges and tunnels. |
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Real-time, Video over IP Surveillance System |
| Modern tunnel management systems have benefited greatly from the use of video cameras, which provide real-time information for traffic controllers who are responsible for controlling and monitoring road signs, light signals, emergency situations, ventilation, and tunnel lighting. Newer and cost-effective cameras with the ability to send good quality compressed figure files require more bandwidth. Therefore, video over IP has become very important for surveillance and safety aspects. Moreover, operators can easily acquire video images over an IP network anytime, and from anywhere. |
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Rugged design in Unpredictable, Harsh Environments |
| The ability to monitor, detect, and recover immediately from system failure is mandatory for safety-critical tunnel applications. To further enhance system reliability, industrial-type products that have a rugged design, high MTBF (Mean Time Between Failures), and extended operating temperature range (e.g., -40 to 75°C) are required for ensuring the security of the tunnel communication system. |
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| Moxa's Networking Solution |
| Safety and reliability are the first
priority when creating a tunnel management infrastructure.
Moxa
provides a range of industrial device networking solutions
that can be used to form a communication network to access
all traffic data from field equipment at different sites
in a timely manner. By emphasizing reliability, affordability,
and versatility, Moxa's solutions include industrial
Ethernet switches, serial device servers, embedded computers,
media converters, and video servers. There are many reasons
why Moxa's products are a good choice for creating
a network communication system for tunnel applications: |
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