Trezzo Bridge
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Reconstructive drawing (surviving parts in dark grey)[1]
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| Coordinates | 45°36′42″N 9°31′20″E / 45.61167°N 9.52222°E / 45.61167; 9.52222 |
| Carries | Two overlapped lanes for pedestrian, horses, carts, and wagons |
| Crosses | Adda River |
| Locale | Trezzo sull'Adda, Capriate San Gervasio |
| Characteristics | |
| Design | Arch bridge |
| Material | Sandstone |
| Total length | 72.25 metres (237.0 ft) |
| Width | 9 metres (30 ft) |
| Height | 20.7 metres (68 ft) intrados |
| Longest span | 72.25 metres (237.0 ft) |
| History | |
| Designer | unknown |
| Constructed by | Bernabò Visconti |
| Opened | 1377 |
| Closed | 1416 |
| Location | |
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The Trezzo sull'Adda BridgeorTrezzo Bridge was a medieval bridge at Trezzo sull'AddainLombardy, Italy, spanning the Adda river. Completed in 1377, the single-arch bridge held the record for the largest span for over four hundred years, until the beginnings of the Industrial Age,[2][3][4][5] while it was not until the early 20th century that masonry bridges with larger openings were constructed.[6]
The Trezzo Bridge was built between 1370 and 1377 by order of the lord of Milan Bernabò Visconti.[2] Fortified with towers, it provided access to the Visconti Castle high above the Adda.[2] During a siege in 1416, the condottiero Carmagnola deliberately caused the structure to collapse by weakening one of its abutments.[2]
Its single arch featured a span of 72 metres (236 ft),[2][3][4][7] according to other sources even as much as 76 m (249 ft).[8] By comparison, the second largest pre-industrial bridge vault, the French Pont de Vieille-Brioude, spans 45 m (148 ft).[2] The rise of the segmental arch was ca. 21 m (69 ft), with a span-to-rise ratio of 3.3:1.[2] The arch rip, measured at the springing, was 2.25 m (7.4 ft) thick,[2] corresponding to a favourable ratio of rib thickness to clear span of only 1/32. The sandstone bridge was almost 9 m (30 ft) wide.[2] Today, the two abutments with overhanging remnants of the arch vault are all that remain.[2]
The Trezzo Bridge was not matched until the metal Wearmouth Bridge of the same span was built at Sunderland, England, in 1796.[9] Longer masonry arch spans were not achieved until the 1903 Adolphe BridgeinLuxembourg.[6]
