A.To.S. – Save Crash REinforcing Weak Soil is a reinforcement device that can be applied directly to the posts of the barriers installed on the road, along embankments or, in general, to barriers embedded in weak soils, there by ensuring considerable savings in terms of time and money and avoiding the need to remake or to consolidate the embankment.
The PIN model or the A.To.S. model, will be selected according to the type of soil in which the system is to be installed:
– A.To.S. – screwed model;
– PIN – frame model.
The problem
In order to install a road barrier, it must be crash tested in a test house and certified by a notified body that declares it in conformity with the provisions of the European standards.
The barrier’s correct behaviour is guaranteed by the correct interaction between its post and the soil it is installed in.
For these conditions to occur in situ, it is necessary that the soil in which the barrier is installed have the same characteristics of those in which it has been tested.
In most installation sites, this does not occur and, when a vehicle crashes into them, the barriers are incapable of acting correctly by containing the vehicle and redirecting it back onto the roadway.
The solutions usually adopted not only fail to solve the problem but are also quite expensive.
How it works
In those situations in which the posts of the safety barriers do not behave as during the crash test due to soil weakness, A.To.S. system provide them with the necessary strength by transferring the impact loads to the road pavement subgrade that has stronger mechanical characteristics than those of the embankment.
The anchorage system will allow the post to bend in a predefined spot and, via its plastic deformation, correctly dissipate the energy of the impact, similarly to what happens during a crash test.
When to install it
A safety barrier post installed in a soil with low mechanical characteristics when impacted, as in case of incident caused by a vehicle, rotates rigidly and this phenomenon causes the failure of the whole barrier. Due to this fact, the vehicle leaves the carriageway without being contained and redirected.
The installation of A.To.S. system guarantees to a barrier installed in a weak soil to perform correctly. The device is indeed able to avoid the rigid rotation of the post assuring the formation of the plastic hinge of the post where expected. This gives strength to the whole system and allows it to reach the same performances of the ITT.
The system’s strenghts
1. Ensures the correct behaviour of the barrier
2. Quick installation without the need of a fixed work site
3. Low cost of production and installation
4. Bespoke designed: applicable to any kind of steel and concrete road barrier
5. Applicable on existing barriers and new installations
6. No maintenance required
7. In the event of impact against the barrier, the device does not require replacement
8. No visual/landscape impact because it is installed below ground surface level
Design and installation
PHASE 1
Assessment using dynamic testing of the minimal performance of the barrier posts via the evaluation of
the interaction between post and soil of the Test House.
PHASE 2
Execution of dynamic tests on the same post in situ so as to compare the real values with those obtained
in the Test House. Based on these results, it is decided whether there is the need of installing A.To.S.
system or not.
PHASE 3
Designing and sizing of A.To.S. system.
PHASE 4
Execution of dynamic tests in situ to assess the correct behaviour of the A.To.S. system and comparison of obtained data.
PHASE 5
In the event of positive outcome, the A.To.S. system is installed.
Validation
The way the system operates has been tested and validated using numerical simulations as well as crash tests conducted in Test House on the same barrier installed in soils having different geometrical configurations.
