Sicily: local early warning system for the San Leonardo Viaduct

CAE has created a local early warning system for the San Leonardo Viaduct, along the SS121 Palermo-Agrigento, in Sicily, a task commissioned by Bolognetta S.c.p.A. for ANAS Sicilia.

It is a hydrometric early warning system with 3 measuring points in as many sections, between the San Leonardo River and the Azziriolo Stream. Each point is equipped with a WLR radar hydrometer  for level measurement and are all acquired by a single Mhaster datalogger.

Through the hydraulic models, the flow values corresponding to the hydrometric levels of interest were obtained, then used to define the alert thresholds for each of the 3 hydrometers. These thresholds contribute to determining the station status, which can be:

• normal;
• alert;
• pre-alarm;
• alarm.

When one or more thresholds are exceeded, therefore in the event of increasing hydrometric levels, the datalogger can enter one of the afore-mentioned states that involve different types of actions: in particular, when entering an alarm condition, the automatic system proceeds to limit vehicular traffic, activating the traffic lights located on the side of the road, one for each direction of travel on the viaduct. In addition, the station sends an alert report to the control centre.

The data are constantly sent to the ANAS monitoring centre and, should an event occur, an alarm system comes into operation notifying the operator that an alert is in progress and it is therefore necessary, depending on the degree of severity of the event, to closely monitor the situation or to intervene directly on site with operators.


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