The Autostrada A4, or Autostrada Serenissima ("Serenissima motorway"), is an autostrada (Italian for "motorway") 523.1 kilometres (325.0 mi) long in Italy located in the regions of Piedmont, Lombardy, Veneto and Friuli-Venezia Giulia which connects Turin and Trieste via Milan and Venice crossing the entire Po Valley from west to east.
The city of Venice (or rather, Mestre, a mainland frazione of Venice) originally formed a bottleneck on the A4, but is now bypassed by the Passante di Mestre (the old route through Mestre was renumbered A57). The A4 passes just north of the city of Milan, where it is toll-free. It is a part of the E55, E64 and E70 European routes.
Due to the different companies that manage the different parts of the motorway, it is often referred to as formed by five sections: Turin-Milan, Milan-Brescia, Brescia-Padua, Padua-Venice and Venice-Trieste. As it runs through the whole Pianura Padana, which is a densely populated and highly industrialized area, A4 is one of the most trafficked motorways of Italy.
Before World War II, three sections of the motorway were built: Turin-Milan, Milan-Brescia and Padua-Venice. The first section built was Milan-Bergamo, which opened on 24 September 1927, being just the second motorway to open, following the Autostrada dei Laghi in 1924/25. On 29 August 1931, it was extended to Brescia. On 25 October 1932, the Turin-Milan section opened, and on 15 October 1933, the Padua-Venice section.
The two sections became connected on 10 February 1962, when the Brescia-Padua section opened. The Venice-Trieste section was opened on 22 February 1970. The original road through Mestre, now designated A57 and named "Tangenziale di Mestre", opened on 3 September 1972.[1]
A4 is a dual-carriageway, six-lane motorway for most of its length. The stretch between Milano Est tollgate and Bergamo has been an eight-lane motorway since 30 September 2007. The stretch from Venice to Trieste is instead still a four-lane motorway, but it is planned to upgrade this stretch over motorway to six lanes.
The passante di Mestre is a part of the A4 motorway, opened to traffic on 8 February 2009. The objective of the route is to reduce the volume of auto- and truck-based traffic passing through Mestre (a mainland frazione of Venice) to reach non-local destinations like Austria, Slovenia and other Eastern European countries.
The new includes three lanes plus one emergency lane. Each lane measures 3.75 metres (12.3 ft) apart from the emergency lane which measures only 3 metres (9.8 ft), and the new stretch of motorway totals 32.3 kilometres (20.1 mi).
Autostrada A4 Passes through Turin, Settimo Torinese, Novara, Cusano Milanino, Cinisello Balsamo, Monza, Bergamo, Brescia, Verona,Vicenza, and Padua.
