Center-to-Center communication
involves the communication between two or more central management
systems. Examples of Center-to-Center communication applicable to the
Bay Area ITS Architecture include:
- Two or more traffic signal
management systems exchanging information (including second-by-second
status changes) to achieve coordinated operation of traffic signals
managed by the different systems and to enable personnel at one center
to monitor the status of signals operated from another center.
- Sharing of transportation
related information with other Bay Area agencies or systems such as
511.
- Providing real-time
information such as transit vehicle predictions.
- Posting a warning message on
another agency’s changeable message sign.
The NTCIP Center-to-Center protocols are
particularly relevant as they allow agencies to exchange information,
to monitor conditions in other agencies’ systems, and to
implement coordinated responses to incidents and other changes in field
conditions when needed. Such data exchange and coordinated response can
be implemented either manually or automatically. One agency can
monitor, and issue basic commands to field devices (if authorized)
operated by another agency, even though those devices may be from a
different vendor than those used by the monitoring agency.
If Agency A wants to
control Agency B’s traffic signals, Agency A sends a message to
Agency B to ask for and be granted permission to control the signals.
This is an example of Center-to-Center communication.
NTCIP Center-to-Center (C2C) protocols are implemented currently though
multiple standards. More information on the current status of NTCIP
standards can be found at NTCIP.org.
The major Center-to-Center projects in the Bay Area use a variety of
standards. DATEX ASN (Data Exchange protocol/Abstract Syntax) is used
by Silicon Valley-ITS (SV-ITS Program), East Bay SMART Corridors, and
the Bay Area Center-to-Center System.
The Bay Area
Center-to-Center System includes 511, SV-ITS and SFgo. The SFgo
connection to the Center-to-Center system is a DATEX to eXtensible
Markup Language (XML) conversion. XML is one of the a Center-to-Center
communications protocol standards. It has the advantage of being an
industry wide standard (across all Microsoft Windows-based systems
regardless of the application) and can be implemented relatively easily
with “typical” information systems staff.
Until XML becomes an
accepted standard in the Bay Area, it is recommended that a Center-to-Center Task Force be developed to monitor changes in standard
development and deployment and make recommendations to agencies
implementing projects. The existing Center-to-Center Working Group
could be expanded beyond the interim Center-to-Center project to take
on the new responsibility of recommending Center-to-Center standards
for projects throughout the region. This Task Force or Working Group
would be coordinated with Architecture Maintenance efforts to ensure
that the Architecture is updated accordingly.
