Milan–Bologna railway

When the state railway company, Ferrovie dello Stato, was established it inherited a diverse range of rolling stock from the former rail companies. Track was in a poor condition and the maximum speed on the line was 80 km/h and then only for specially-equipped trains, with slower speeds over bridges and points. Therefore, FS had to proceed with the reconstruction of bridges and viaducts, track and points in the stations, signalling and safety equipment.

Only after this work was finished in the 1910s could the new powerful Italian 690 Pacific steam locomotives be introduced; they were designed specifically for flat and fast lines but had a very high weight per axle compared to locomotives previously used in Italy. In the 1920s improvements to the line finally allowed train operation at up to 100 km/h for the fastest trains. Only in 1929 was the line adequate for loads of 20 tons per axle; even then this required slowing to 20 km/h on the long iron bridge over the Po near Piacenza until its replacement by a new bridge. After its opening, the average commercial speed on the line was raised to 87 km/h.

Starting in 1927, the Milan–Bologna line was the site of the first major trial of in-cab signalling, with the signalling information passed by magnets. This system was designed by the engineer Gino Minucciani. The successful experiment was followed in 1928 by the equipping of the line to Bologna for the repetition of two types of signals: stop and go; if the driver did not comply the braking system would be automatically applied. The 690 locomotives were equipped with this system.

In the late 1920s the limits of steam began to become clear, especially in terms of its high operating costs and its limited potential for further acceleration. It was decided to electrify the line at 3,000 volts direct current following excellent results achieved in experiments, although the Porrettana line between Bologna and Florence had been electrified with a three-phase alternating current system in 1927, and this system was proposed for the new Bologna–Florence direttissima. During the same period the ever-increasing traffic on the line, which had become the primary axis of the Italian railway network, began to saturate the capacity of the stations in Bologna, and a rail bypass was built to its north.

The bridge over the Po built in 1931 and rebuilt after the Second World War.

Following the electrification of the line in 1938, Minucciani's system of in-cab signalling was abandoned because it was considered too expensive to equip the electric locomotives with it. Instead FS tested a new system of automatic block signalling designed by Minucciani on a 110 km stretch of line. Although these tests were successful it was not implemented because investment in that period prioritized the speed and punctuality of trains for propaganda reasons rather than innovation in safety devices. In 1939 a train hauled by ETR 212 travelled from Milan to Bologna in just 77 minutes, while the normal speed for express trains had been reduced to 105 minutes.[11]

In 1991, a deviation of the line was activated between Milano Rogoredo station and San Giuliano Milanese station, on which the new stations of Borgolombardo and San Donato Milanese were built.[12] (the latter was only opened in 2003). This deviation was necessary to enable the construction of the "fast line" on the alignment of the original line.

The quadrupling of the section between Milano Rogoredo station and Sordio junction, just before San Zenone al Lambro station, was completed in 1997. However, due to the postponement of development work at Milan Rogoredo station, it was not possible to adequately upgrade rail services, in particular the planned suburban railway service.

In 2002, work began on the construction of the Milan–Bologna high-speed railway, which connects to the old line in the municipality of San Zenone al Lambro. The line from there to Milan had already been quadrupled. The high-speed line was opened in 2008, after the interconnection in Tavazzano was completed on 29 May 2005.[2]

The line from Milan Rogoredo to Lodi has been served by line S1 of the Milan suburban railway service since 13 December 2009.

The line starts at Milano Centrale and runs along the belt railway, along with the lines to Venice and Genoa, passing through the stations of Milano Lambrate (where it separates from the line for Venice), Milano Forlanini and Milano Rogoredo, where it separates from the line for Genoa. The line between Rogoredo and San Giuliano Milanese has been doubled since 1991 with the construction of the fast line on the historic route and the building of the stations of San Donato Milanese (which was not actually opened until 2003[14]) and Borgolombardo.[12]

Since 1997, the line to Sordio junction (before San Zenone al Lambro) has been quadrupled by the construction of a new line that bypasses the town of Melegnano and that is used by traffic to and from the high-speed line.[15] Shortly after Melegnano, the historic line and the new line cross the river Lambro on two separate bridges.[16] After San Zenone, the line passes through Tavazzano station, which, since 2005, has been linked by the Interconnessione di Tavazzano (Tavazzano interconnection) between the historic line and the new line that it used by high-speed traffic.[2]

The section between Casalpusterlengo and Codogno is shared with the Pavia–Cremona railway. After Santo Stefano Lodigiano station, the railway crosses the Po in Piacenza over a bridge. which was built in 1931 and 1932 and replaced the previous single track bridge built in 1865; it consists of 11 pairs of iron beams, with a parabolic upper arch, six of these have a span of 74.52 m, and five of 61.02. Lines branch off in Piacenza to Alessandria and Cremona.

Near the city there are two links with the high-speed line: the Piacenza west interconnection,[17] located just before the bridge over the Po and the Piacenza east interconnection,[17] located just after the city.

After Piacenza the railway runs parallel to the Via Emilia (state highway 9) passing through Pontenure, Cadeo, Fiorenzuola d'Arda and Alseno. It enters the territory of Province of Parma, at Fidenza, where lines branch off to Cremona, Fornovo and Salsomaggiore Terme and there is an interconnection with the high-speed line.[17] The next station, Castelguelfo has a freight yard. The line arrives at Parma where lines branch off to La Spezia, Brescia and Suzzara, while to the east of the city, there is another interconnection with the high-speed line.[17] The line enters the Province of Reggio Emilia, which is the location of the stations of Sant'Ilario d'Enza, Reggio Emilia (the terminus of the three lines of the Ferrovie Reggiane) and Rubiera. The line enters the Province of Modena, where the lines to Mantua and Modena, and Sassuolo branch off in Modena station.

Frecciabianca service passing through Cavazzoli, Reggio Emilia

In November 2014, a deviation was opened between Rubiera and Modena that is more than 8.5 kilometres long, including an almost 2 km-long tunnel. This was built as part of the construction of the high-speed line and the simultaneous upgrade of the traditional line. The new route, located farther north than previously, avoids crossing the western part of Modena and is connected to the Verona line by means of a link line. Marzaglia freight yard was opened on the new line.[18] In Modena there are also two interconnections with the high-speed railway, one to the west and one to the east of the city.[17] After Castelfranco Emilia, the railway enters the Metropolitan City of Bologna, which includes the stations of Samoggia and Anzola dell'Emilia. The last interconnection with the high-speed line is near Lavino junction.[17] In the last kilometres before Bologna Centrale station, where the line ends, the railway runs parallel to the lines from Verona and Pistoia.

• Coletti, Giovanni (1978). Il passaggio delle ferrovie dall'amministrazione privata all'amministrazione pubblica nel 1905 (in Italian). CIFI.
• Gallio, Silvio (2009). Oggi è un'ora di viaggio - La costruzione della strada ferrata tra Milano e Bologna (in Italian). Bologna: CLUEB. ISBN 978-88-491-3173-4.
• Mascherpa, Erminio (1997). 691 compromesso vincente (in Italian). Salò: Editrice ETR.
• Mascherpa, Erminio (1992). Ripetizione segnali e vigilanti (in Italian). Salò: Editrice ETR.