MAINTENANCE ASPECTS - The Westerschelde Tunnel: Approaching Limits - page 281

maintenance-friendly. Aside from that, inspection facilities had to be applied
with which the life span and the reliability of the various (main)sections of
the structure could be determined. In addition, the (main)sections had to
be accessible, and finally the cable gallery had to be accessible from both
mainland ends. The last two conditions were amply complied with. Both
cable galleries are accessible from both ends and extensive attention was
paid to the accessibility of all (main)sections.
Maintenance-friendly design In respect of the first condition - a
maintenance-friendly design - it can be noted that the attention in the first
instance, was particularly geared towards the realization of functionality,
whereas the check pertaining to a maintenance-friendly implementation or
design occurred to a limited degree.The maintenance-friendly design was a
recurring theme during the preliminary consultations between KMW and
NV Westerscheldetunnel. This is reflected particularly in the layout of the
tunnel, in which almost all the installations are accessible for maintenance
when a single driving lane (and not a whole tunnel tube) is closed off.
Monitoring system In order to determine the reliability of the tunnel
construction, inspection facilities have been applied on a limited scale so
as to (particularly) monitor the leak water and the quality of repairs to the
lining. With the facilities that were applied in the first instance however, it
was insufficiently possible to be able to make credible statements about
the quality of the lining. That is why an arrangement was made with the
contractor to further extend the monitoring programme into a representative
measuring programme.
Aside from the quality of the lining, the functioning of the tunnel installa-
tions is naturally of critical importance for the tunnel users. In order to keep
an eye on the reliability of the installations, two tracks were worked out: on
the one hand a large number of faults are signalled directly to the tunnel
operator which meant that an on-line monitoring programme as it were,
was used. On the other hand the inspection schedule is worked out in the
maintenance plan on the basis of a chance-of-failure analysis. In this the
results of the inspections are expressed in a chance-of-failure, which if neces-
sary, provides the input for the actual maintenance activities.
Fig. 18.8
Maintenance