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“an accurate analysis of the compatibility of the new trains with the existing rail network”

Laser rail survey of narrow-gauge railway lines in Sardinia





Implementation period


Services provided

Laser Rail survey of railway lines;
Structure Clearence and derailment assessment


The railway network run by ARST S.p.A is composed by five narrow-gauge lines in Sardinia, for a total development of about 205 km, articulated as follows: Monserrato – Isili of 71 km, Macomer – Nuoro of 60 km, Sassari – Alghero of 30 km, Sassari – Sorso of 10 km and Sassari – Nulvi of 34 km. The network was built in the first half of the twentieth century, using criteria inspired to economic savings, that led to a very tortuous layout with relevant dimensional limits.
In view of the major investments planned for the renewal of the rolling stock fleet, it has been decided to assess the structure clearence of the new diesel-electric Stadler railcar on the entire ARST network, through a detailed verification of the compatibility of the shape of the new train with the Minimum Profile of Obstacles (PMO) recognized on the infrastructure.
The analysis has been performed through an innovative continuous detection system , integrated with some static surveys in particularly critical points. The system used , called MMS – Mobile Mapping Systems “ Laser Rail “ , consists of a platform, installed on the railway cart, to which are connected and synchronized more survey tools such as laser scanners, digital cameras, inertial platforms, GPS system and PC for storing data.
This system can provide a vast set of data, both topographical – consisting
of point clouds detected by the laser scanner – and video-based or geo-referenced images, allowing a recognition of all the elements that compose the shape of the rail infrastructure. The system range is approximately 150 meters.
After the field activity, the data have been verified and processed in order to reconstruct the three-dimensional model of the entire network.
It has therefore been tested the compatibility of the infrastructure with the outline profile (static and kinematic profile footprint) of the new railcars; the assessment highlighted some problems, both on the rail line (punctual interferences with the outline of some artworks, and more diffusely, with the vegetation) and with the station platforms. The data collected via the Laser rail system allowed, in addition, to verify the derailment point of the rolling stock in various driving conditions.

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