Extensive repairs were carried-out to this structure between 1988 and 1992. During these works, a total of 289 cracked limestone blocks had to be carefully broken-out from the piers and replaced with concrete (the latter being poured and moulded in situ). Approximately 500 square metres of pointing (the mortar between the stone blocks) was replaced and more than 1,200 stainless steel rock anchors (a.k.a. 'grip bar anchors') were installed to tie the masonry together. These repairs are clearly visible when the structure is viewed close-to (as shown in this photograph). However, when the viaduct is viewed from a moderate distance, the repairs become almost invisible.
If you look closely at the lower portion of this photograph, you will see a significant number of angular stone blocks scattered across the ground. Very few of these are left-over debris from the repair works. In most cases, they have fallen from the structure in recent years and they offer very clear evidence of the power of rain and frost to shatter solid rock. Blocks of stone (ranging in width from just a few centimetres to several tens of centimetres) may fall from the structure at any time: you are therefore advised NOT to linger beneath (or in close proximity to) this structure.