The 139 mile (224 km) long route built in 1971 – 1977 between Silesia – Zawiercie – Włoszczowa – Idzikowice – Grodzisk Mazowiecki – Warsaw, known as the Central Mainline (Polish acronym:CMK), was the largest investment of Polish State Railways after the war. It provided a new connection between Silesia and the capital city of Poland where trains could travel at up to 155 mph (250 km/h). The expected weight of freight trains was 5 thousand tons. However, due to the lack of proper equipment and in connection with track-level railway transport, the maximum speed was reduced to 100 mph (160 km/h). Travelling at such speed was possible, among other things, thanks to the new design of traction network which was completely compensated, had two catenaries and special suspension. The only stop for passengers on this route is Włoszczowa Północ. From 2006 three express trains stopped there. Currently, it is a stop for most TLK and InterRegio trains.
The plans provided for extending the mainline from Warsaw through Wyszogród, Płock, Sierpc, and Malbork to Gdańsk. Some investments were even commenced but because of the economic crisis in the People's Republic of Poland the works were suspended. On 11 May 1994 CMK established a new speed record in Central and Eastern Europe. During tests, an Italian Pendolino train reached 155.41 mph (250.1 km/h).
Broad Gauge Metallurgy Line
Another large project completed during the times of the Polish People's Republic was the construction of a 245 miles (394 km) long broad-gauge, non-electrified line originally referred to as the Hrubieszów-Huta Katowice Line, later Metallurgy and Sulphur Line. At present, it is known as: Broad Gauge Metallurgy Line (Polish acronym: LHS). Built in 1976 – 1979, it was routed from the railway border crossing in Hrubieszów to the Sławków Południowy railway station in order to enable transport of iron ore from Krzywy Róg directly to the Katowice Steelworks. Sulphur, extracted near Staszów, and coal mined in Silesia were among the goods transported by this line in the opposite direction.
At the end of the line and along its route transfer terminals are situated. Currently, they are used for unloading all types of goods imported to Poland from Ukraine and from other countries of the former Soviet Union. In 1990 – 2000 long-distance passenger trains from Russia and Ukraine travelled irregularly on that route. Platforms for passengers were built at the stations in Hrubieszów and Olkusz and passenger stops in: Zamość Północny, Wola Baranowska and Sędziszów Północny. In 2001 the line was acquired by PKP LHS.
Electricity is the key
The electrification of railways progressed quickly. In 1978 the construction of electric traction was completed along with the refurbishment of the Poznań – Szczecin Główny line (133 miles, i.e. 214 km). One year later it reached Goleniów, and in 1980 – Świnoujście. Also, the East-West Mainline was electrified: Poznań – Zbąszynek (1979) – Rzepin (1984), Łuków – Biała Podlaska – Terespol (1980) – state border (1981). The speed of works increased up to 311 miles (500 km) a year. Domestic manufacturers were not able to provide a sufficient number of rolling stock, so in the 1970s locomotives had to be imported from Czechoslovakia (ET40; 60 units) and the USSR (ET42; 50 units). In the critical year – 1981 – electric trains departed from Zgierz to Kutno and from Herby through Wieluń to Kępno. In total 4,350 miles (7,000 km) of railway lines were electrified.
After martial law was introduced, railways were “militarised”. A continued major investment was the electrification of the Odra line: Wrocław – Głogów – Zielona Góra – Rzepin – Kostrzyń – Szczecin Główny (1985; 213 miles, i.e. 342 km), Bydgoszcz – Toruń Główny (1984) – Kutno (1985), and the Tczew – Malbork – Iława – Działdowo – Nasielsk line (146 miles, i.e. 235 km), which provided the shortest efficient connection between Gdańsk and Warsaw.
Other lines subject to electrification were: the Wrocław – Legnica – Miłkowice – Węgliniec (1985) – Lubań Śląski – Jelenia Góra route (1986) and Warsaw – Białystok – Kuźnica Białostocka (1986). In 1984 – 1987 electric trains ran from Tarnów through Stróże – Nowy Sącz – Muszyna to the state border with a connection to Krynica. Only in 1988 did electric traction reach Koszalin, Kołobrzeg, Olsztyn, Dęblin, Piła and Szczecinek and one year later – Słupsk and Żywiec. In 1990 electric service was provided on the lines to Przeworsk (Przeworsk – Rozwadów line), Wadowice and Elbląg. At that time Polish State Railways electrified more than 6,214 miles (10,000 km) of lines.
In addition, after 1990 the electrified lines Wrocław – Kłodzko – Międzylesie (1994) and Elbląg – Olsztyn (1994) were put into operation. Further electrification was suspended.