Gully Monitoring via the Iridium Satellite Network for Highways Accident Reduction


This week saw the deployment of a unique system with the potential to reduce road traffic accidents by producing early warnings of blocked drains, roadside gullies, and road flooding via the Iridium satellite network.

Optimised for rapid, retrofit deployment without the need of a pre-survey (no cellular coverage required), the system can be installed without the need for changing the gully covers, drilling within the gully to fit mounting brackets, or cutting the road surface for cabling. In all, eliminating need for road closures and keeping both installation cost and disruption to an absolute minimum whilst maximising operative safety.

The RDNET1000 Wireless Gully Sensor

The Gully Sensor utilises RDN’s unique BDT solid-state smart sensor technology which has already seen over a decade of reliable service in sectors from utilities to railways, monitoring drains, sewers, and river levels. In this application the BDT is supplied with a unique magnetic mounting bracket that permits it to snap onto the existing gully’s grating like a limpet mine, and simultaneously enable the high-water trigger point to be set from as little as 8in (20cm) right down to 14ft (450cm) below the road surface.

The RDNET1000 Wireless Gully Sensor Installed

The Gully Sensor is 100% sealed for life, to beyond the requirements of both NEMA 6P and IP68 hence able to withstand total submersion when the road floods. Frugal in power consumption, the BDT Gully sensor combination has already demonstrated a battery life in service of greater than ten years, despite reading the level and transmitting the data every 2.5 seconds.

Virtually invisible from the road surface – a fully deployed

Gully Sensor has no impact on traffic flow or safety

Rapid reading and reporting is essential for the system to be able to detect flooding with a high degree of confidence and not create false alarms. Typically, if 10-sucessive 2.5 second interval data packets from a particular sensor are not received within a 30-second window then the system errs on caution and interprets the sensor as being submerged and out of communication.

The Iridium Satellite Gateway is designed by RDN to pick up the wireless signals emitted by the Gully Sensors reporting a high level in the chamber and when totally submerged the loss of signal is interpreted as road flooded. The Gateway just like the gully sensor is designed for retrofit installation, supplied housed in a lightweight GRP enclosure with a pole strap mounting bracket for affixing to a light column, or roadside up-stand. The gateway can be battery or solar powered keeping the system autonomous of the existing highways infrastructure.

Battery Powered Iridium Gateway –

 Installed on a small lighting column

System Example

A typical gully monitoring system could comprise of a small number of gully sensors deployed in the lowest lying gullies along the section of road liable to flooding and an associated Iridium Gateway mounted roadside.

The system example below is a live installation comprising of two gully sensors located at the side of a dual carriageway at an underpass that is liable to flooding, where the Iridium Gateway reports via a VPN to a data server that issues SMS texts and emails to emergency response teams.

The Iridium Gateway is mounted on the lamp column on the left hand side of the carriageway just outside the underpass where it has moderate visibility of the sky and hence access to the iridium satellite network. In this example the distance between the furthest sensor and the gateway is 60ft (20m) however distances of up to 300ft (100m) can be supported.

Although the example depicts an urban setup, the system is equally deployable in ultra-remote locations. In the absence of street furniture, the gateway can be mounted on an upstand or equally mounted in a roadside kiosk or bollard.

The system can also include a mixture of sensors capable of reporting blockages in culverts, drains, and trash screens. The system is also equally applicable for use on railway networks.

For further information please contact Radio Data Networks

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