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Checking perceptive admissibility
for construction
of a motorway bypass

Spea has checked the design of a motorway bypass with a reduced cross-section which is required due to the periodic reactivation of the landslide which affects the road near two viaducts.

Description of the works

The bypass will consist mainly of an embankment structure. The design provides for the temporary use of the bypass in the event of new landslides which may adversely affect the stability of the two viaducts until safe conditions are restored.

Verification procedure

The check was carried out in accordance with article 10 of a regional law which specifies the use of a human viewpoint approach.
A film taken on site together with mapping that describes the actual current condition was used to reconstruct the true situation of the infrastructure in the section in question in the form of a virtual model. The design of the bypass has been entered in this model. The virtual model of the current situation was then compared with the design, to simulate travelling along that section of motorway from the viewpoint of a motorist with the relative perceptive capacity. The comparison has enabled certain critical points to be identified where the new structure was actually perceivable. This comparison concluded and demonstrated that the perceptive alterations resulting from the design were globally negligible since they did not show any appreciable modification of the fields of view for an observer from the viewpoint of the user.