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Media-conversion technology aids system-wide approach to support interoperability and accommodate transportation-management needs.
Responsibility for traffic flow and dispatching emergency and maintenance vehicles for one of the North America's busiest highway systems falls on the California Department of Transportation (Caltrans) District 11 control centre. District 11 manages the transportation challenges for the greater San Diego area, encompassing 290 closed-circuit televisions and 466 traffic-monitoring stations. The department's primary objective is to improve safety and quality of life for California citizens of the San Diego area by optimising traffic flow and ensuring the most efficient response from emergency and maintenance vehicles.
District 11 needed to connect various field elements - including closed-circuit television, ramp meters, changeable message signs and communication-networks to the traffic-management centre (TMC). In its initial research, district staff realised that any potential solution would require a system-wide approach to support interoperability and accommodate transportation-management needs well into the future.
The problem, according to David Dutcher, project engineer for Caltrans, was "to find a global solution at a reasonable cost, that would be efficient, cost-effective, provide easy maintenance and meet the unknowns coming up in transportation management in the next 20 years.
"With San Diego growing and traffic increasing, we felt that we had to be proactive in providing transportation management (and) trying to meet the needs of the public in the growing demand for efficient transportation systems."
According to Ross Cather, engineering project manager at Caltrans, "Our dilemma was to lease infrastructure from a provider, which would have been very expensive to operate and often unreliable, or to construct a state-owned fibre-optics communication infrastructure. While providing greater reliability, constructing our own fibre-optics system required special skills to manage - skills not typically available within the department's workforce."
The final choice for District 11 was to build a state-owned fibre infrastructure. District 11's choice was based on long-term savings, flexibility and the reliability that owning its own fibre infrastructure would provide. To address concerns with the internal skill level, District 11 developed a partnership with the Headquarters Department of Information Technology (HQ-IT) to design a fibre-optics communication system based on technologies already being used as part of the department's IT program.
"Many of the technology decisions were driven by the desire to match what the IT group was already developing for the more traditional IT network communication efforts," states Cather.
The final system design consists of a combination of products. A pan-tilt and zoom-capable camera is mounted on traffic station pole tops. The camera is connected to a video codec encoder, mounted in an enclosure at the base of the camera pole. A media converter from Transition Networks is used to convert the copper interface from the codec to fibre to transport the data back to the TMC.
Remote device information
A chassis-based media converter is used at the TMC to convert back to copper and connect to the Cisco switch. Intelligence within the media-conversion devices located at the remote traffic station allows District 11 to monitor and obtain information about remote devices, such as power and link status.
One of the initial design issues the district needed to address was how to incorporate legacy RS232 equipment already in place. Any new deployment would need to replicate the same communication protocol, regardless of the technology selected.
The end devices - 170 controllers - run various types of software, encompassing changeable message sign, traffic signal, ramp meter and surveillance software. Each end device transports data using a variation of the RS232 protocol, so any new solution would have to support RS232 signalling. District 11 also needed to keep the ability to communicate with discrete devices throughout the region's infrastructure and add closed-circuit cameras to monitor traffic.
District 11 initially focused on an ATM-based solution to accommodate its legacy RS232 equipment requirements. The ATM ability to channelise data and control data flow without isolating specific data streams was an essential part of integrating the district's low-speed RS232 devices throughout the region.
During the evaluation process, District 11 identified as a potential fit an encoder that used the entire RS232 protocol, enabling the analog video feed from the traffic cameras to be converted into a digital signal. The Baxall encoder is a copper-based piece of equipment, which required District 11 to evaluate conversion products in order to facilitate communication over fibre to the TMC.
"That encoder was the foundation for a lot of the solution and our technology decisions were based on this," states Dutcher.
In addition to protocol, various solution components required extensive evaluation for durability and overall fit. Solution components included traffic video cameras and equipment used to digitise the information and transport it over fibre to the TMC. The traffic cameras gave District 11 increased flexibility in the equipment deployed.
An initial 'hiccup'
This new environment still needed to support the RS232 protocol, as did the cameras selected for the project. When evaluating the different products on the market, District 11 found that many of the manufacturers had products that supported IP-level 422 transports to a greater extent than the RS232. Capitalising on this advanced technology, the district decided to use an open-standard video camera, allowing the district a wide variety of options.
The first hiccup in the project development came from an unexpected source. In the 1990s, the state developed the Department of Information Technology (DIT). In conjunction with the Department of Finance, the DIT works on developing standards for state IT solutions. The DIT produced the State Feasibility Studies Report (FSR), which identified Ethernet IP as the standard communications protocol for IT-related solutions. Under this directive, the original ATM solution that District 11 selected needed to be replaced with an Ethernet IP-based solution.
To incorporate an Ethernet-based solution, District 11 required a device to convert the copper interfaces into fibre and transport the data back to the TMC. The district also had to identify products to transport the legacy protocols, such as RS232, which were uncommon at the time.
In the evaluation process, District 11 found few manufacturers that could meet its stringent requirements, and found only one component capable of full protocol transport for RS232. Once potential component manufacturers were identified, extensive bench testing and field testing were performed with sample products. The evaluation process spanned several years, due to the rapid changes in technology and the slow internal project-development process. District 11 began evaluation early in the project-development stage and continued evaluating product to the time the purchase order was written.
Evaluation of products
The evaluation process for media conversion was more streamlined. District 11 viewed conversion in a straightforward manner, with product robustness, intelligence and warranty the key criteria. Staff evaluated product field performance within the environment the district had planned to operate it in.
Another of the district's challenges was power failure in the field. During evaluation, media converters from Transition Networks were the only conversion products found on the market that provided power failure information from remote units. "That provided a huge amount of value to us. We felt the more automation we could provide to the system, the more benefit a particular product had to us," explains Dutcher.
On-time product delivery and installation issues also challenged the district. According to Dutcher, "Just getting physical bodies out there to install it (was difficult) because we were breaking new ground in our procurement and our implementation. It had not been done anywhere in the state; in fact, the method used probably had not been done anywhere."
An important issue was having enough skilled people that understood the technology and the installation. In addition, installing the equipment was outside the scope of normal state responsibilities. In the end, the team that would have ultimate responsibility for maintenance and support would also have to install the equipment. An outside vendor was brought in to leverage its expertise in the installation and testing process.
District 11 also faced a technology ramp-up issue. Although the engineers had appropriate training for managing and maintaining the traffic system, they lacked specific expertise in new technologies, such as Ethernet.
"The state does not have the resources to hire full-time outside resources to manage and maintain, so we have to find ways to do it ourselves. The best way to leverage those dollars is to train internal people," states Dutcher. District 11 used an outside training company and, although the training caused some delay in the project, it was critical to its overall success.
Financing the system
The district chose to use the California Multiple Awards Schedule (CMAS) for its procurement method. The CMAS program required District 11 to make a best-value selection by evaluating direct cost, maintenance and the ability to manage the systems. Maintenance and remote-management capability represented a significant cost over the life of the project. Remote management, diagnostics and warranty thus were important considerations.
"Right now, our resources are limited in terms of staffing and we do not have the ability to go out and do a lot of heavy diagnostics," Dutcher says. While evaluating media-conversion products from Transition Networks, Dutcher says, "We found that we could provide an end device that had a certain level of intelligence in it that allowed remote-management information to be sent to our local facility that could decrease the amount of maintenance and evaluation."
Although staff followed the Ethernet IP directive from the DIT, the overall selection and decision to purchase was made within District 11. Dutcher and others within District 11 decided to avoid submitting the solution for a public bid because of the probability of an 'or/equal' vendor applying. An or/equal could be viewed as a viable solution, though, in reality, would compromise the specific needs of District 11. Using the CMAS program allowed District 11 to avoid the potential issue.
District 11 has already realised savings by having realtime access to accurate information. Awareness of traffic situations allows the TMC to access situations and proactively address potential impacts on traffic systems. With up-to-date information, the TMC is minimising the impact of traffic issues. The new infrastructure also allows future IP-enabled products to be deployed that will provide more value for overall operation needs.
"Using much of the same technology deployed in the HQ-IT's WAN, we were able to leverage the IT program's knowledge base and resources," says Cather. "The end result was a state-of-the-art, IP-based fibre-optic system that is very scaleable and can be operated and managed more efficiently."
For more information contact Hennie Faurie, Fibre Cable Equipment, +27 (0)12 651 2333, [email protected]
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