A Variable Message Sign (VMS) is an electronic sign used on roadways to provide real-time information about traffic conditions, accidents, road closures, construction delays, speed limits and other traffic information. The Department of Transportation (DOT) in a large metropolitan city implemented a successful VMS program on its primary roads where network infrastructure was already in place. In order to deploy the same program on the secondary arterial roads proved problematic, since implementing a hardwired network on the older highways would require cost-prohibitive trenching and under-roadway drilling to lay fiber.
The DOT learned about the Digi Connect WAN, the industry’s first upgradeable, commercial-grade 3G cellular router, provides high performance, secure wireless communications over cellular to connect remote sites and devices. The centralized VMS control system in the traffic management center communicates to each sign via a wireless/cellular network connection – a physical wired connection is not required. Since the cellular network is not vulnerable to outages caused by line breaks or other wired network problems, operators can update the signs whenever needed.
The Digi Connect WAN provided several key benefits to the DOT:
- Instant deployment – wireless connectivity eliminates wiring costs and problems due to wire breaks
- Seamless interfacing with existing VMS control systems enables real-time updates
- Wireless carriers offer low data rate plans based on airtime used
- Meets bandwidth requirements for good video frame rates
- Operating temperature range of -30° C to 60° C ensures durability in extreme temperatures along the roadways
With the Digi Connect WAN, the metropolitan DOT is able to deploy VMS signs citywide using cost-effective cellular technology. Traffic managers are able to provide valuable traffic data as it occurs, giving commuters time to plan alternative routes to avoid areas of extreme congestion, thus easing gridlock for the entire community.
Deploying variable message signs on arterial roadways without existing network infrastructure
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Connect serial traffic devices in remote areas to traffic management centers via wireless/cellular technology