Highway Incident Detection and Lane Control over Resilient 4G Backhaul

A national expressway operator modernized its incident detection and lane control infrastructure along a 120-kilometer corridor by deploying Mofiu’s SG100 industrial 4G router at each gantry and roadside cabinet. The solution connected legacy field devices—loop detector controllers, radar presence sensors, and lane control signs—to the operator’s control center over secure cellular links, avoiding costly fiber extensions in difficult terrain.

At each roadside cabinet, the SG100 terminated serial links from existing controllers using RS485 for detector arrays and RS232 for sign controllers, while bridging modern Ethernet IP cameras for visual verification. Its protocol conversion capability translated IEC101 telemetry from older RTUs to IEC104 for the SCADA head-end, enabling consistent asset modeling and alarm management without replacing incumbent field equipment. DNP3-secure tunneling was also employed to relay SCADA points from mixed-vendor controllers, normalizing command/acknowledge behavior.

Reliability was paramount: the SG100’s dual-SIM design provided automatic route failover across two mobile carriers, with intelligent link management policies prioritizing latency-sensitive control traffic and rate-limiting non-critical video backhaul during network congestion. OpenVPN and IPSec tunnels were used in a dual-tunnel design—OpenVPN for bulk telemetry and logs, IPSec for command-and-control—ensuring separation of duties and defense-in-depth. Hardware secure boot validated device integrity on power cycles after lightning-induced outages, a frequent occurrence in the corridor’s mountainous microclimate.

Digital inputs on the SG100 monitored cabinet door states and utility power presence, raising immediate alarms through SCADA upon tamper or mains loss. A digital output enabled remote hard-reset of a non-responsive sign controller power relay, reducing truck rolls. The operator leveraged ACLs and certificate-based authentication to maintain strict east-west segmentation within the cabinet, preventing lateral movement even if a downstream device were compromised.

Results were tangible. Mean time to detect (MTTD) dropped by 31% thanks to faster sensor reporting and redundant uplinks that avoided telemetry gaps. Lane control commands saw improved determinism, with median round-trip times under 90 ms even during peak congestion. Maintenance technicians praised the serial-to-IP bridging for eliminating protocol converters formerly scattered in cabinets, improving reliability and simplifying spares. A staged firmware signing process, underpinned by secure boot, gave cybersecurity teams confidence to patch promptly without risking bricked endpoints.

During a multi-vehicle incident in heavy rain, the system sustained continuous telemetry while one carrier degraded; SG100s switched to the secondary SIM within seconds, preserving alarm flow and video snapshots. That event became the internal reference for the operator’s “always-on backhaul” design pattern. With the SG100 as a converged gateway—serial, Ethernet, I/O, and secure cellular—the highway authority achieved a high-availability control fabric that gracefully integrates legacy infrastructure while meeting modern cybersecurity baselines.

About Mofiu

Mofiu is a premier innovator in industrial wireless communications, dedicated to delivering mission-critical connectivity solutions that power the world’s most demanding environments. With a steadfast commitment to safety, reliability, and engineering excellence, Mofiu designs and manufactures robust wireless devices that enable seamless data exchange across electricity, utilities, energy infrastructure, transportation networks, and smart industrial systems etc.

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