Bay area goes wireless to secure bridges, tunnels

In a homeland security project, the California Department of Transportation is using multiple wireless systems to transmit surveillance data from seven bridges and three tunnels in the San Francisco Bay area to a command center in Oakland.

The department, known as Caltrans, has completed the first phase of the $20 million Bay Area Surveillance Enhancement project. BASE includes installation of up to 15 point-to-point wireless links spanning distances of as much as 16 miles each and transmitting data at 90M bit/sec., according to IT industry executives involved in the project. The wireless technology is being tied to 250 video cameras that will use video-over-IP technology to transmit images to the command center.

Caltrans activated the BASE system at two bridges and a tunnel in the South Bay area last month and plans to turn on the rest of the technology in February. Some details of the project are due to be announced this week by Sunnyvale, Calif.-based Proxim Corp., which is supplying all of the wireless equipment.

Greg Bayol, a spokesman for Caltrans, said the BASE system was designed to help the agency and the California Highway Patrol monitor bridges and tunnels for potential security problems. The cameras are being deployed to "watch for anyone who should not be there," Bayol said.

He added that Caltrans chose wireless links instead of fiber-optic cable because of cost issues and the vast distances that the network needs to span in order to reach all the bridges and tunnels.

David Brown, a division manager at Sacramento, Calif.-based Royal Electric Co., the prime contractor on the BASE project, agreed that cost was a decisive factor in prompting Caltrans to opt for wireless links.

In an unrelated project, Royal Electric recently installed a 3-mile fiber link across one Bay area bridge at a cost of about $3 million, Brown said. He estimated that it would cost $30 million to $40 million just to put fiber-optic cables on all the bridges and tunnels that will be covered by the BASE wireless system.

Layers of Complexity

Open Computing Platforms Inc. in Moorpark, Calif., handled the wireless systems integration work for Caltrans. CEO Steve Williams described the BASE project as one of the most complex that Open Computing has ever done.

The complexity resulted from factors such as the size of the network and the need to install numerous links that cross water, which can cause multipath distortion of wireless signals, Williams said. He added that the project also required extensive frequency coordination to ensure that there won't be any interference between the BASE signals and other wireless transmissions.

That process was further complicated by the fact that BASE uses a mix of licensed and unlicensed spectrum, with most of the wireless systems operating in the unlicensed 5-GHz band, Williams said.

Multiple levels of wireless security protections are being installed in an attempt to ensure that the BASE technology can't be penetrated by unauthorized users, he noted. The protections include the use of Triple Data Encryption Standard algorithms on the signals sent by the video cameras, as well as virtual LANs and the IPsec protocol to provide additional encryption and user authentication capabilities.

In addition, Williams said the Proxim-based wireless subscriber units that are being attached to the video cameras have built-in Global Positioning System receivers. The receivers broadcast the geographic coordinates of each wireless unit to Proxim-built base stations at the bridges. If a subscriber unit is moved, the base station won't accept signals from the new coordinates, he said.

Video camera images are transmitted via wireless links to the point-to-multipoint base stations, which in most cases are connected by Ethernet to point-to-point wireless transmitters that are also made by Proxim.

Ken Haase, director of product marketing at Proxim's WAN division, said the company's equipment operates in the same frequency band as 802.11a wireless LANs. But, he said, the Proxim technology uses proprietary protocols to help boost security and throughput levels.

Copyright © 2002 IDG Communications, Inc.

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