Computer repair las vegas

LAS VEGAS IS THE SITE OF THE 69TH ITE ANNUAL MEETING IN AUGUST. THIS IS THE SECOND IN A SERIES OF THREE FEATURES THAT DESCRIBE THIS INVITING CITY'S TRANSPORTATION ENGINEERING TECHNOLOGY.

THE LAS VEGAS (NEV., USA) Valley has experienced the most rapid growth of any metropolitan region in the United States. According to recent U.S. Census reports, Nevada was the fastest growing state in the nation in 1997 for the 12th year in a row, with Las Vegas being the fastest growing metropolitan area for the seventh straight year. Between 1990 and 1996, the Las Vegas area population grew by about 1,000 people/week, or 41 percent overall, to more than 1.2 million people. These staggering growth rates equate to increasing traffic congestion and air-quality concerns. Public officials in the Las Vegas area have aggressively pursued an ambitious program of public-works improvements to address increasing traffic demand. The efforts include the construction of new roadways and the expansion of existing roadways, the expansion of transit services designed to manage demand for the roadways by transferring travelers to more efficient transportation modes and the establishment of a program for improving the effectiveness of the existing roadway network by upgrading and enhancing the Las Vegas Area Computer Traffic System (LVACTS).

LVACTS is an agency jointly managed by Clark County, the Cities of Las Vegas, North Las Vegas and Henderson, the Regional Transportation Commission of Clark County and the Nevada Department of Transportation. LVACTS was established in 1983 as one of the few multijurisdictional trafficsignal systems in the United States. At the time of its formation, LVACTS installed an urban traffic control system (UTCS) that centrally controlled the majority of traffic signals in the metropolitan area. The existing system reached its capacity of 500 intersections several years ago, and most traffic signals constructed since that time cannot be accommodated on the existing system. In addition, the existing system is considered technically obsolete.

Recognizing the critical need to efficiently manage traffic in the Las Vegas Valley, the Operations Management Committee (OMC), which oversees LVACTS, funded a 1992 feasibility study for upgrading the existing system. Several strategic decisions made by the OMC during the feasibility study led to the state-of-the-art advanced traffic management system (ATMS) currently being implemented. Those decisions include:

* Minimizing the amount of new communications infrastructure that is placed in underground conduit. The existing LVACTS communications system utilizes twisted-pair copper wire in underground conduits and is susceptible to damage from the myriad construction activities of this growing region. Prior to LVACTS hiring staff to repair and maintain the communications system, it took weeks and months before many broken and damaged cables were repaired. This left many traffic signals without coordination. The response to this decision was to design a new communications system that primarily uses wireless communication mediums. This led to the use of 18 Gigahertz (GHz) analog microwave as the backbone of the entire communications network for the system. This was supported by a 900 Megahertz (MHz) data radio system for traffic-controller data and 31 GHz analog microwave for closed-circuit television (CCTV) signals for video monitoring. Only two short runs of fiber-optic cable were installed in underground conduits, and no new copper cable was installed for any long communications runs;

* Utilizing as much of the existing twisted-pair copper cable as possible. The OMC felt a considerable investment had been made in the original twisted-pair cable system, and they did not want to abandon it. Plus, the limited funding that was available made it impossible to replace the copper cable system with more current technology such as fiber-optic cable. This presented a challenge because a majority of the new CCTV cameras to be installed for traffic monitoring were located at intersections that were tied into the twisted-pair cable and had no other communication medium for transmitting video signals. This issue was resolved by using devices from MiL-Lektron Co. that allowed for quality video signals to be transmitted on unused pairs of the twisted-pair cable; and

* Reducing the data load on the communications system for trafficcontroller data passing between the intersection controllers and the LVACTS Traffic Management Center (TMC). This was another outgrowth of the problems experienced with the in-the-ground communications being damaged or destroyed and causing whole portions of the system to be offline for a period of time. This decision led to the selection of the new advanced traffic controller or 2070-type controller that will have the ability to maintain traffic-signal coordination in the event of a communications failure.

The feasibility study evaluated several alternative systems and identified a recommended system based on its ability to provide the highest benefits to the users. Using the results of this study, the Regional Transportation Commission of Clark County included the project in the federally funded Congestion Mitigation and Air Quality improvement program, which was established in the Intermodal Surface Transportation Efficiency Act of 1991. In 1993, the Nevada Department of Transportation, in cooperation with the LVACTS participants, secured the services of Barton-Aschman Associates (now part of the Parsons Transportation Group) to proceed with design and implementation of the new system.

THE NEW LAS VEGAS ATMS

In the past, traditional traffic-signal systems were designed to control traffic signals in the field controller units from inside a traffic-control center. The existing LVACTS is an example of this highly centralized approach. On a second-by-second basis, the central computer directs the individual actions of every traffic signal that is part of the system. If communications to the central computer are lost, the traffic signals fall back to local control, and signal coordination is most frequently lost. This approach requires a large central mainframe computer and demands a very reliable communications capability between the central computer and the intersection controllers.

The new system follows an approach consistent with the fundamental principles of distributed processing, which assigns system functions to the system components where the process is actually needed. This approach resulted in the development of a system that locates the real-time control of intersections at the local intersection controller level, which places the responsibility for communications at the hub computers and for display reports and engineering databases at the TMC. This type of system offers the following distinct advantages:

* Improved reliability;

* Ease of expansion;

* Less reliance on communications infrastructure;

* Easy to upgrade; and

* Flexibility

The distributed processing system architecture utilized in the upgraded LVACTS is illustrated in Figure 1.

LOCAL INTERSECTION CONTROL