Trezzo sull'Adda Bridge

The Trezzo sull'Adda Bridge or Trezzo Bridge was a medieval bridge at Trezzo sull'Adda in Lombardy, 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,[1][2][3][4] while it was not until the early 20th century that masonry bridges with larger openings were constructed.[5]

The Trezzo sull'Adda Bridge provided access to the Visconti castle over the Adda. At the left-hand side, one abutment with remnants of the sharply rising arch vault is visible.
Hypothetical reconstruction of the bridge. The surviving parts are in dark grey.[6]


The Trezzo Bridge was built between 1370 and 1377 by order of the lord of Milan Bernabò Visconti.[1] Fortified with towers, it provided access to a Visconti castle high above the Adda.[1] During a siege in 1416, the condottiero Carmagnola deliberately caused the structure to collapse by weakening one of its abutments.[1] Its single arch featured a span of 72 m,[1][2][3][7] according to other sources even as much as 76 m.[8] By comparison, the second largest pre-industrial bridge vault, the French Pont de Vieille-Brioude, spans 45 m.[1] The rise of the segmental arch was ca. 21 m, with a span-to-rise ratio of 3.3:1.[1] The arch rip, measured at the springing, was 2.25 m thick,[1] corresponding to a favourable ratio of rib thickness to clear span of only 1/32. The sandstone bridge was almost 9 m wide.[1] Today, the two abutments with overhanging remnants of the arch vault are all that remain.[1]

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 Bridge in Luxembourg.[5]

See alsoEdit


  1. ^ a b c d e f g h i j Hans Straub et al. (1992), p.79f.
  2. ^ a b Donald Hill (1984), p.72
  3. ^ a b Ervan G. Garrison (1999), p.123
  4. ^ Leonardo Fernández Troyano (2003), p.93
  5. ^ a b M. G. Lay, James E. Vance (1992), p.268
  6. ^ G. Crivelli (1886), table 1
  7. ^ Leonardo Fernández Troyano (2003), p.116
  8. ^ Colin O’Connor (1993), p.188
  9. ^ Leonardo Fernández Troyano (2003), p.49


  • Ariberto Crivelli: Gli avanzi del castello di Trezzo - L'antico ed il nuovo ponte sull'Adda, Milano, 1886
  • Colin O’Connor: Roman Bridges, Cambridge University Press, 1993, ISBN 0-521-39326-4
  • Donald Hill: A History of Engineering in Classical and Medieval Times, Routledge, 1984, ISBN 978-0-415-15291-4
  • Ervan G. Garrison: A History of Engineering and Technology, CRC Press, 1999, ISBN 978-0-8493-9810-0
  • Hans Straub et al.: Die Geschichte der Bauingenieurkunst. Ein Überblick von der Antike bis in die Neuzeit, Birkhäuser, 1992, ISBN 978-3-7643-2441-4
  • Leonardo Fernández Troyano: Bridge Engineering. A Global Perspective, Thomas Telford Publishing, London 2003, ISBN 0-7277-3215-3
  • M. G. Lay, James E. Vance: Ways of the World: A History of the World's Roads and of the Vehicles That Used Them, Rutgers University Press, 1992, ISBN 978-0-8135-2691-1

External linksEdit

Coordinates: 45°36′43″N 9°31′24″E / 45.612052°N 9.523202°E / 45.612052; 9.523202