Assessment and maintenance plan for 36 structures near Coentunnel - Amsterdam

The ring of Amsterdam is ongoing for an enlargement. One of the bottlenecks is the passing under the North Sea canal in Amsterdam. This passing is named the Coentunnel, named by a famous Dutch officer of the Dutch East Indie Company.

Building a new tunnel below the canal now doubles this tunnel.

At both sides of the Coentunnel traffic exchangers are build, 36 of this structures needs to be maintained by the Coentunnel construction company.

Before a maintenance plan could be made, an in depth assessment of the constructions was done. A number of bridges and tunnels were grouped; if they were build at the same time, with the same method, the same design, the same concrete.

This resulted in 9 groups of constructions. Of each of these groups one construction was assessed : the abutment, columns, decks and if possible the foundations were investigated.

Al these elements were assessed to Chloride induced corrosion, Carbonation induced corrosion, Alkali silica reaction, Delayed ettringite formation.

The Chloride induced corrosion was done by measuring the chloride distribution on minimal 3 cores, and concrete cover, resulting is the calculation of the initial chloride content, diffusion coefficient and surface chloride content. With these parameters the remaining lifetime is calculated. If the functional lifetime did not meet the specified lifetime, addiditonal maintenance measures were engineered.

At the end a series of maintenance plans were edited in order to guarantee the functionality of the structure during the maintenance period and until the end of lifetime period.

Special to these assessments was that the procedure was conforming ‘systems engineering’ like mentioned in ISO 15288.