Centralna Magistrala Kolejowa (line 4 Grodzisk Mazowiecki – Zawiercie)

Chainage km 1.091 – 80.608 (79.517 km). Original opening 1977 in two parts. 200 km/h was introduced on this 80 km section on 10 December 2017. Overhead line Szeligi – Idzikowice (km 24.023 – 79.309, 55 km over both tracks): contract signed on 20 June 2012 with PKP Energetyka, net value PLN 65.9 million including design, with completion planned by 5 June 2013 (the report does not say it was completed). Line 4 also carries ETCS level 2 works on Korytów – Zawiercie (PLN 361 million for the whole 210 km, not split by lot, basis not stated).

Chainage km 80.608 – 124.808 (44.2 km). Original opening 1974. Named contracts: Idzikowice station and local control centre, Budimex and KZA Lublin consortium, design-and-build, PLN 106 million (basis not stated), works from February 2018, final acceptance in June 2020, two weeks before the contract deadline. Opoczno Południe station (km 92.142), design and works with a second platform, Porr Polska Construction S.A. (spelt "Porr Polska Construcion S.A." in the source), contract signed 16 May 2017, almost PLN 55 million (basis not stated), works planned for 2017–2019. Olszamowice station, Budimex, design and works worth almost PLN 45 million (basis not stated), completion reported on 21 August 2018. The Pilichowice junction post (km 106.588) opened on 11 August 2017. About 40 km of overhead line between Idzikowice and Olszamowice has been replaced.

Chainage km 124.808 – 224.915 (100.107 km). Original opening 1974. Scheduled 200 km/h service with ED250 Pendolino began on 14 December 2014 between km 125.2 and 212.2, excluding the Włoszczowa Północ station area and a stretch with level crossings (76.82 km in total); in March 2017 the 200 km/h stretch was shortened to 58 km (km 156.496–214.800) for the station works. Włoszczowa Północ station (km 154.39), second platform: contract signed in early November 2016 with Trakcja PRKiI, PLN 57 million net, works planned to the end of May 2018; the new platform opened on 11 August 2017. In March 2024 PLK described works on this lot: Psary – Zawiercie track renewal worth PLN 305 million, Knapówka junction post PLN 38 million, Zawiercie station PLN 96 million (basis not stated for these three, contractors not named). The PLN 361 million ETCS level 2 contract covers Korytów – Zawiercie, across all three lots. Speed on the line was lowered from 200 to 160 km/h in 2024 while ETCS level 1 was switched off; PLK says 250 km/h needs ETCS level 2 and GSM-R, with GSM-R tests planned for August 2026 in a PLK release of 16 April 2026 (not cited here).

Single-track electrified link between Czarnca junction on line 61 and Włoszczowa Północ on line 4, allowing trains from Kielce to enter the CMK northwards. The length is the 5.025 km in PLK's line list (Id-12, as cited on plwiki); PLK's press release calls it a three-kilometre link and the 2017 report gives about 3.2 km, which is also what is drawn, so the drawn line is shorter than the recorded length. The 2017 press report put the total cost at almost PLN 50 million with VAT, of which PLN 40.2 million net for ZUE. At completion PLK gave the project value as about PLN 42.8 million (basis not stated). Passenger trains up to 100 km/h, freight 80 km/h. The press forecast of December 2019 for opening was missed. Plwiki says works were reported begun in early July 2018 but that, because of plot-division problems, they actually started at the end of 2020, so no construction start is recorded.