feasibility study of real time parking information at ... - WMATA.com
feasibility study of real time parking information at ... - WMATA.com
feasibility study of real time parking information at ... - WMATA.com
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<strong>WMATA</strong> Real-Time Parking<br />
Inform<strong>at</strong>ion Feasibility Study<br />
Communic<strong>at</strong>ions<br />
Chapter 6: PILOT PROJECT CONCEPT<br />
Communic<strong>at</strong>ion between field devices and with other agencies is expected to use fiber<br />
optic technology, 10/100 Ethernet, or a hybrid <strong>of</strong> the two. Media converters will be<br />
needed to interface between Ethernet-based devices and fiber optic cabling. These are<br />
available <strong>at</strong> rel<strong>at</strong>ively low cost, and are not expected to significantly impact overall<br />
system costs.<br />
Space level detectors most <strong>of</strong>ten utilize an ASI Bus system in which the power and d<strong>at</strong>a<br />
typically transmit along the same Siamese cable (two wires in parallel) to low voltage<br />
devices (32 volts typical). ASI Bus technologies have been proven to save enormous<br />
amounts <strong>of</strong> capital costs during deployment. A single bus type cable is deployed<br />
between the device controller and its associ<strong>at</strong>ed sensors. Each run length <strong>of</strong> bus<br />
cabling can ac<strong>com</strong>mod<strong>at</strong>e up to 62 devices with a distance limit<strong>at</strong>ion <strong>of</strong> approxim<strong>at</strong>ely<br />
330 feet, extendable to approxim<strong>at</strong>ely 985 feet with the use <strong>of</strong> a repe<strong>at</strong>er.<br />
Figure 6-11 shows a potential <strong>WMATA</strong> architecture for connectivity between devices in<br />
any <strong>of</strong> the <strong>parking</strong> facilities.<br />
Once the d<strong>at</strong>a is connected to the <strong>WMATA</strong> fiber in the st<strong>at</strong>ion <strong>com</strong>munic<strong>at</strong>ions room, it<br />
will be transmitted to the central server room for <strong>WMATA</strong>. There it will be connected to<br />
the new Parking Central Server. This server will connect to other systems internal to<br />
<strong>WMATA</strong> as required (e.g., <strong>of</strong>fice LAN, web server). The <strong>com</strong>munic<strong>at</strong>ions to the internet<br />
will be through the existing <strong>WMATA</strong> web server. This includes publish/subscribe<br />
services to VDOT. Until such <strong>time</strong> as a direct fiber connection is available, the internet<br />
can be used to share <strong>inform<strong>at</strong>ion</strong> between the two agencies.<br />
Additional load on the current web server will only require the addition <strong>of</strong> a dedic<strong>at</strong>ed<br />
Active Server Page (ASP), or the integr<strong>at</strong>ion <strong>of</strong> the additional <strong>inform<strong>at</strong>ion</strong> into an existing<br />
ASP webpage, to facilit<strong>at</strong>e incremental or <strong>real</strong>-<strong>time</strong> upd<strong>at</strong>es. The scripts within the ASP<br />
architecture will request, receive, and publish <strong>inform<strong>at</strong>ion</strong> from the equipment controllers<br />
as assigned by the webmaster.<br />
While the additional responsibilities placed on the web server and IT staff are assumed<br />
to be marginal, this project does afford an opportunity for the agency to upgrade the web<br />
server. This price is not included in the estim<strong>at</strong>e for this project.<br />
Page 6-15 June 2009
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