| Advanced Communications In Transportation |
| Premises Wiring: Designing the Infrastructure
of an Information Network |
| By Larry Kelly, Atlanta, Georgia, 1-404-870-3208,
c/o mjohnson@ogc.itsmarta.com |
| Connectivity is the lifeblood of a network. It transforms
a facility to an office and makes the remote seem as if it is next
door. Poor design choices can cripple an operation. Knowledgeable
design choices can reduce cost, increase productivity and support
future growth. |
|
MARTA Communication Activities
• Supervisory control and data acquisition (SCADA)
• Train control
• Closed circuit television
• Fire detection and alarm
• Intrusion detection
• Maintenance radio
• Customer relations
• Building automation
• Telephone
• Public address
• Fare collection
• Maintenance management information system
• Visual public address system |
Premises wiring seldom shares the limelight in the design of a comprehensive
communication system. Yet, this discipline provides the critical infrastructure
that supports information networks. Wiring affects costs, productivity,
efficiency and competitiveness, and it controls the future of most
of today’s organizations.
Wiring represents only about five percent of the network cost and
even less of the construction costs in an average network installation.
In contrast, many industry experts believe that wiring is responsible
for 50 percent to 80 percent of network failures and that it is a
major factor in limiting data network performance. While the actual
impact of network failures is difficult to quantify, most people have
felt their effects—be it in getting through a frustrating sales
transaction, seeing a processing plant shutdown or waiting for a delayed
train.
Several Integrated Communication Activities
MARTA’s system-wide communication network integrates several
functional systems that use different technologies for communications
and control capability. Several communication activities (see box
below) at various facilities are integrated into a network using the
technology appropriate for the application. These technologies include
fiber, copper and wireless.
MARTA’s premises wiring designs must support the systemwide
communication goals of an open architecture using standard modular
interfaces that embrace current technology.
Keeping the Design Up-to-Date
Our premises wiring design has evolved and been kept up-to-date as
MARTA’s transit system grows (at a rate averaging almost two
facilities per year during the last twenty-five years (as technology
evolves. Yet, our communications system continues to be comparable
with existing low-demand facilities and it is upgradeable to meet
expanding communication requirements.
Our design begins with the criteria, which are evaluated continually.
Our engineers must stay in tune with operations and be informed of
the developments within the industry in order to:
- Accommodate MARTA’s growth
- Incorporate the technological advancements
within the industry
- Provide practical solutions to meet our
users’ ever-expanding need for additional operational and
maintenance data.
Next, we conduct an analysis of the operational requirements for each
targeted facility. Using the criteria, analysis results, and cost
of installation and maintenance, we determine the topology and medium
necessary to meet the client’s application. This includes choosing
copper, fiber or wireless and structuring it to meet future expectations.
The forces that drive our premises wiring are the appetites for bandwidth
to the desktop and the necessity of network availability. Never have
the selections of the medium and the location of the communications
closets within a facility been more important.
Going “The Last Mile”
Premises wiring is included in the industry coin phrase “the
last mile.” In an ideal design, premises wiring can be upgraded
without additional facility cost, providing a structured cabling system
that addresses several specific engineering design rules. These rules
incorporate the characteristics of open architecture, standard connection
interfaces, and modular installation to make the premises system manageable.
MARTA Customer Information Operator Center consoles showing
AVL bus positions |
Our system-wide design provides communications and control services
from the rail services central control facility to each facility and
along the track. Our communication engineers strive to have this system
operate with the reliability of the telephone and the capability of
the Internet. It is our goal that the communication network system
be available and seamless to the user. To meet this goal, we follow
a systematic design approach, use commercially available structured
modular components and use them in an open architecture.
Smart Choices are Important
Our work has continued to support MARTA’s growth, including:
- Expansion of the rail system with new track
and station facilities
- Renovation for a new bus facility
- Installation of information networks, which
include a traffic management and information system that was installed
during preparation for the 1996 Olympic Games and shared with
the Georgia Department of Transportation.
Knowing the key elements of cable management, available equipment,
and the changes occurring within the industry is necessary to a good
design and vital to a successful operation. Knowledgeable design choices
have provided a communication system that allows MARTA to incorporate
new technologies, enhancing the capabilities without impacting their
service to the patrons. These new technologies will give MARTA an
infrastructure that will assist in providing quality service well
into the new millennium.
Premises wiring should be a major element in the overall design package
when assessing the communication requirements and planning the future
capabilities for each facility. For new facilities, premises wiring
issues should be addressed during initial design. Our MARTA experiences
have shown that making smart choices in this area of design is vital
to a quality transit operation.
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| Larry Kelly is a communications engineer responsible
for the remote terminal units, fare gates, special facilities and
supporting telephone networking for MARTA. |
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