Double-track railway in the context of "South West Main Line"

The railway from Athens Airport to Patras is a double-track, standard-gauge railway line in Greece that, when completed, will connect Athens International Airport with Patras, the country's third-largest city. One of the largest railway projects of the last 30 years in Greece, its completion is of major significance for the infrastructure of the entire region of the northern Peloponnese. As of 2020, the line is completed until the city of Aigio. A 5.2 km underground section is planned for the final section from Kastellokampos to Agios Andreas in Patras, terminating at the new port of Patras. For most of the section between Athens Airport in East Attica and Mandra in West Attica, the line runs along the median strip of the Attiki Odos motorway.

A single-track railway is a railway where trains traveling in both directions share the same track. Single track is usually found on lesser-used rail lines, often branch lines, where the level of traffic is not high enough to justify the cost of constructing and maintaining a second track.

The railway from Piraeus to Platy is an electrified double-track railway line that connects Athens to northern Greece and the rest of Europe. It constitutes the longest section of the mostly completed higher-speed rail line known as P.A.Th.E./P., which includes Greece's most important rail connection, that between Athens and Thessaloniki. Its northern end is the station of Platy, on the Thessaloniki–Bitola railway. In the south, it connects to the Athens Airport–Patras railway at the Acharnes Railway Center. The line passes through Thebes, Katerini and Larissa, and offers connections to several other cities (Chalcis, Lamia, Volos, Karditsa, Trikala) through branch lines.

The Providence and Worcester Railroad (P&W; reporting mark PW) is a Class II railroad operating 612 miles (985 km) of tracks in Rhode Island, Massachusetts, and Connecticut, as well as New York via trackage rights. The company was founded in 1844 to build a railroad between Providence, Rhode Island, and Worcester, Massachusetts, and ran its first trains in 1847. A successful railroad, the P&W subsequently expanded with a branch to East Providence, Rhode Island, and for a time leased two small Massachusetts railroads. Originally a single track, its busy mainline was double-tracked after a fatal 1853 collision in Valley Falls, Rhode Island.

The P&W operated independently until 1888, when the New York, Providence and Boston Railroad (NYP&B) leased it; four years later, the New York, New Haven and Hartford Railroad obtained the lease when it purchased the NYP&B. The P&W continued to exist as a company, as special rules protecting minority shareholders made it prohibitively expensive for the New Haven to purchase the company outright. The New Haven continued to lease the Providence and Worcester for 76 years, until the former was merged into Penn Central (PC) at the end of 1968. Penn Central demanded the shareholder rules keeping P&W alive be rewritten, and also threatened to abandon the company's tracks. In response, a group of P&W shareholders launched a fight with PC, asking the Interstate Commerce Commission (ICC) to cancel the lease and let the P&W leave the New Haven's merger and go free. Against expectations, the ICC agreed, and after court battles, P&W prevailed and began operating independently again after 85 years. Upon regaining its independence, the railroad purchased railroad lines from the Boston and Maine Railroad and PC successor Conrail in the 1970s and 1980s. The company turned a profit operating lines bigger companies lost money on, and invested heavily in its infrastructure. P&W also absorbed a number of shortline railroads in Connecticut and Rhode Island.

The main line, or mainline in American English, of a railway is a track that is used for through trains or is the principal artery of the system from which branch lines, yards, sidings, and spurs are connected. It generally refers to a route between towns, as opposed to a route providing suburban or metro services. It may also be called a trunk line, for example the Grand Trunk Railway in Canada, or the Trunk Line in Norway.

For capacity reasons, main lines in many countries have at least a double track and often contain multiple parallel tracks. Main line tracks are typically operated at higher speeds than branch lines and are generally built and maintained to a higher standard than yards and branch lines. Main lines may also be operated under shared access by a number of railway companies, with sidings and branches operated by private companies or single railway companies.

Rail transport in Germany is provided predominantly by Deutsche Bahn (DB, lit. 'German Railway'). As of 2021, the railway network in Germany (DB only) had a length of 33,399 km (20,753 mi), of which 20,540 km (12,760 mi) were electrified and 18,556 km (11,530 mi) were double track. About 1,658 km (1,030 mi) are high-speed railway lines. Germany has the 6th longest railway network in the world, and the largest in Europe after Russia.

Germany was ranked 4th among national European rail systems in the 2017 European Railway Performance Index assessing intensity of use, quality of service and safety. It had a very good rating for intensity of use, by both passengers and freight, and good ratings for quality of service and safety. It also captured relatively high value in return for public investment with cost to performance ratios that outperform the average ratio for all European countries.