IRR Transversal Line

The IRR Transversal Line or the Haditha-Kirkuk Railway (Route Number 4) is a railway line of the Iraqi Republic Railways that connects Haditha and Haqlaniyah with Kirkuk via Bayji. It is a single-track unelectrified line. The railway is about 252 km long and has a maximum travel speed of 100 km/h. Unlike other Iraqi rail lines, it does not end at Baghdad. At present, the railway line is operational for freight transport only between Haditha and Baiji. However, the damaged truss-bridge over the Tigris has halted the resumption of services to Kirkuk. The railway line's state is notably deteriorated, reflecting the widespread disrepair and of Iraq's rail infrastructure.

Technical specifications
The railway line had a fully automatic electric centralized traffic control system since its inauguration in 1987. The railway line possessed a network of telegraph cables running parallel to the rails which provided connections between the stations and locomotives. As of October 2018, the signalling and communication systems are both out of service.

The line has two light maintenance workshops at Kirkuk and Haqlaniya and one heavy maintenance factory at Baiji.

The track gauge is 1435 millimetres (standard-gauge). The rails have a UIC 60 profile and consist of welded joints. The axle load is 25 tons.

Early developments and metre-gauge railway
Ever since the latter half of the 19th century, a railway line to Kirkuk was discussed but due to the Great War construction was postponed. Eventually, construction on the Kirkuk Railway Station commenced in 1925 while the foundations for the Kirkuk-Baghdad-Haifa Railway were laid beginning in 1930. The idea of the section from Baghdad to Haifa was abandoned due to the Arab-Israeli War. In 1949, a 105-kilometre extension to Erbil had started with a steel bridge over the Great Zab River near Al-Tun and the first train arrived in Erbil by 1950. An undertaking for an extension to Sulamaniya was initiated by the then Iraqi Director of Railways Major General Saleh Zaki Tawfiq in 1963. Still, it was eventually abandoned with the regime change in 1968. It is to be noted that the current Transversal Line and the aforementioned railway only minimally share trackage.

Standard-gauge railway
It was planned by the Ba'athist Regime to replace the original railway with a standard-gauge railway. They renewed the idea of also extending the line to Sulaymaniya. However, after further consideration, it was decided to construct a brand-new standard-gauge railway from Kirkuk to Haditha with an interchange at the Berlin-Baghdad Railway at Baiji The construction of the railway line started on August 26th, 1982. Still, because of the Iran-Iraq War, the opening was delayed. The new line opened in 1988. A ground-breaking ceremony by the then Minister of Communication Mohammed Hamza Al Zubaidi was held on November 7th, 1987. The cost for the construction of the new line was 960 million USD.

The metre-gauge railway that connected Erbil and Baghdad via Baquba and Kirkuk was closed in 1984 by the Office of the Presidency of the Iraqi Republic. The new railway made the old connection obsolete. Due to the retrofitting of the IRR Southern Line from metre-to standard-gauge in 1964, the old railway lost its interoperability with it. Other, unstated reasons were to not only connect Kirkuk better to other Sunni Arab areas in the west of Iraq to make Arabisation easier, but to also cut off railway access to Kurdish areas following the autonomy of Iraqi Kurdistan in 1970. As a result, many landmarks along the old line, such as the Erbil Railway Terminal, the Baba Kiwan Junction, multiple bridges, and various facilities such as hotels and hospitals, were demolished. It was the last railway of its type in Iraq.

Another reason for the relocation of the route was the now double connection of the Haditha oil refinery, in the west of Iraq, to the Iraqi railway network, but also to the north of Iraq.

Recent progress
On November 8, 2022, the Baiji Field Branch was rehabilitated by the Central Government. That way freight trains are able to once again travel between Baghdad and Qaim. Currently, there is no progress on rehabilitating the Kirkuk Branch due to the ongoing conflict between Baghdad and Erbil over the disputed territories of Northern Iraq, of which Kirkuk is part.