Hundreds of billions of dollars are being spent on railway construction worldwide as countries improve transportation options for passengers and freight. These long-distance connections often traverse mountain ranges, waterways or dense urban environments, requiring expensive bridge, viaduct and tunnel solutions.

Construction costs vary wildly – especially for high-speed rail – from an average cost per kilometre of $18.5 million (£15m) in Spain to a whopping $175 million (£139m) in the UK, according to a 2023 report from the Spanish government. What's more, budget and schedule overruns are typical for these complex and extensive engineering works.

Read on to discover the biggest railway megaprojects currently under construction (ranked in order of cost) and find out when they'll be completed.

All dollar amounts in US dollars.

The ferry service between the island of Lolland in Denmark to Fehmarn in Germany can take 45 minutes, but that will no longer be the case by 2029 when the Fehmarnbelt Fixed Link opens. This combined road and rail project is an 11-mile (18km) immersed tunnel being constructed on the seabed of the Fehmarn strait between Germany and Denmark, and it will be possible to cross it in as little as 10 minutes for cars and seven minutes for trains.

Wider railway transport in Europe will get a huge boost too when the project is completed, with freight transport journeys between Scandinavia and Central Europe reduced by 100 miles (160km). Meanwhile, passengers will see shorter travel times between Copenhagen and Hamburg, with journeys falling from five hours to under three.

Following a decade of planning, construction started in 2020 on the Danish side of the project. The first two concrete elements – sections of the tube tunnel – floated out of the factory in February 2025 in preparation for immersion (pictured).

The project, which includes railway expansion work on either side of the tunnel, will cost €10 billion ($10.5bn/£8.3bn) to build. When it's completed and operational in 2029, it's expected to be the world’s longest tube-immersed tunnel.

In 2024 alone, more than 14 million cars and trucks drove through the 4,500-foot-high (1,371m) Brenner Pass, the mountain range between Austria and Italy. Heavy traffic can pose a safety risk – the picture shows a truck fire from 2019 – so to shift vehicles off the roads and onto rail cars, the 34-mile (55km) Brenner Base Tunnel will enable freight transport between Innsbruck in Austria and Fortezza in Italy through the mountains.

The project is highly complex, requiring the excavation of two tunnels, each 27 feet (8m) wide to accommodate one rail track and running 130-230 feet (40-70m) apart. It also requires a smaller exploratory tunnel driven through the rock before the two main tubes, which will later be used for drainage once the line is in operation. On top of that, there are numerous connecting tunnels, side tunnels and other access tunnels.

Construction is well underway and the exploratory tunnel has been fully excavated, but it’s by no means been easy. One of the project’s many tunnel-boring machines got stuck in a fault zone for seven months in 2023, and there are several other fault zones the machines must cross before finishing excavations. The line is expected to open in 2032.

None of this heavy civil construction and engineering comes cheap, though the final price wasn’t actually clear from the outset. Austria had calculated the total cost to be €9.6 billion ($10bn/£8bn), whereas Italy worked it out to be a little bit less at €8.8 billion ($9bn/£7.3bn). However, neither is the correct number at this point. According to the latest estimates from 2023, the project sponsors now expect the total cost to end up around €10.5 billion ($11bn/£8.7bn).

Looking to reduce its dependency on oil and focus on more sustainable development, the UAE launched its Etihad Rail initiative in 2009. This 745-mile (1,200km) railway network across the nation will serve both freight and passenger services, linking all seven emirates to Saudi Arabia. It's also part of the wider Gulf Cooperation Council rail project.

Construction has progressed inconsistently. Work started immediately in 2009, and by 2016, freight services were in operation for a 164-mile (264km) portion of the line. Work started on another section of line connecting Abu Dhabi to Fujairah in 2020 and opened three years later. That same year, a separate project to connect Dubai and Abu Dhabi was completed, marking the milestone of fully operational freight rail.

Etihad Rail celebrated the 'maiden voyage' of a passenger train in January 2024. However, the actual opening date of the railway for passengers remains unknown. To top it off, in January 2025, plans for a new high-speed line connecting Dubai and Abu Dhabi were announced. This will reduce journey times to just 30 minutes from 57 minutes.

The total cost for developing Etihad Rail is $11 billion (£8.7bn). The cost of the new high-speed line has yet to be revealed, but estimates suggest it could be around $3 billion (£2.4bn).

Upgrading the existing line between Palermo and Catania, this rail project will improve transportation connections between the coastal urban areas of Sicily and inland locations.

One of the big drivers behind the modernisation project is to encourage more rail travel by reducing journey times and improving accessibility. Converting 110 miles (178km) of rail into an electrified double-track railway is expected to increase speed and capacity.

While many sections of the existing railway will be repurposed, there’s ample new construction involved in the project. The region’s hilly terrain requires much of the alignment to run through tunnels and over viaducts, which will need to be built first.

Construction started in 2018 with an anticipation of finishing the works by 2025. However, many sections are not expected to be in operation until as late as 2030. The total cost is estimated at €11 billion ($11.6bn/£9.2bn).

There’s also a massive rail modernisation programme underway in southern Germany, which aims to improve railway connections in and around Stuttgart and reduce travel time for rail journeys between Frankfurt and Munich. The project includes building a new high-speed line to Ulm (pictured), which went into operation in 2022.

Planning for the project dates back more than 30 years. Upon completion, the programme will include 35 miles (56km) of tunnels, 42 bridges, four new stations and 62 miles (100km) of new track, as well as a new station in Stuttgart.

Construction started in 2010 with a scheduled completion date of 2019. However, a lengthy list of protests, delays and disputes has repeatedly set the project schedule back, with tunnel work eventually wrapping up in 2023. Currently, the new system is expected to be operational before the end of 2026.

Unsurprisingly, the project’s costs have skyrocketed from €4.5 billion ($4.7bn/£3.7bn) in 2009 to €11 billion ($11.6bn/£9.2bn) today.

For much of the 20th century there was passenger rail between Los Angeles and Las Vegas – including a boozy weekend-only line called the 'Las Vegas Fun Train' in the early 1970s. However, by 1976, all the fun had ended and services ceased to exist.

Officials have long explored options for creating a new west coast link between the two cities and eventually proposed the DesertXpress in 2005. The project struggled to find both supporters and funding; although organisers made various deals with third parties such as China Railway International USA and Virgin Trains over the following 15 years, these all fell through. Finally, a private firm called Brightline, which has been building rail projects in Florida, acquired the project in 2019.

Dubbed Brightline West, the new railway will take passengers from Las Vegas to Rancho Cucamonga in California where riders can transfer to commuter rail trains into the city. This allows the project to avoid the expense of construction work in a dense urban environment.

In April 2024 officials held a construction groundbreaking ceremony in Las Vegas, with the expectation that the project will be finished in four years – in time for the 2028 Summer Olympics in Los Angeles.

Company and public officials confirmed that the project has all the required right-of-way and environmental approvals to build the line, which will involve the construction of 160 new structures, including viaducts, bridges and wildlife crossings.

The project is expected to cost $12 billion (£9.4bn) and has secured around half its funding from the federal government. When completed, the line’s electric trains are expected to reach speeds of 200 miles per hour (322km/h) – the fastest in the US.

Over on the east coast of the US, the quasi-public rail agency Amtrak has several rail rehabilitation and modernisation projects underway, the biggest of which is the Gateway Program. Made up of 11 projects, it will improve the most congested 10-mile (16km) section of the Northeast Corridor – the line between Boston and Washington DC – by increasing the capacity from two tracks to four.

The program also includes replacing bridges, expanding New York’s Penn Station and excavating a new tunnel under the Hudson River, as well as rehabilitating the nearby existing 100-year-old tunnel.

In 2024, the US government agreed to cover three-quarters of the costs, with the states of New York and New Jersey picking up the rest of the $16 billion (£12.6bn) bill.

Though the tunnel project was officially given the green light in 2024, construction had already started on early works contracts to prepare the subsurface of Manhattan’s riverside rail yard next to Penn Station.

The twin tube 2.4-mile (4km) tunnel will be built in three separate sections, with the first two already awarded and the third shortlisted in January 2025. The new tunnel is expected to be in service by 2035.

While this railway project is focused on a 135-mile (220km) connection between Salerno and Calabria in southern Italy, once in operation, the benefits will extend up and down the country, reducing the journey from Rome to Reggio Calabria by up to four hours. It will also add new stops along the line.

This requires building new viaducts and tunnels and adding capacity on existing lines, among other infrastructure, to ensure trains are capable of high-speed travel.

Construction is divided into several sections and it's anticipated that as many as 15 tunnel boring machines will be used on the project. These machines cost millions of dollars, especially when they're equipped to handle difficult ground conditions.

Italian contractor WeBuild launched one of these massive excavators in February 2025 to build one of the tunnels through the hilly terrain of the region’s Sele Valley.

In total, this high-speed railway is expected to cost €22 billion ($23bn/£18bn), with partial operation expected as early as 2026 and the final phase finishing in 2032.

In late 2009, Vladimir Putin inaugurated Russia’s Sapsan high-speed train linking Moscow and Saint Petersburg. The service had been designed to reach speeds of 155 miles per hour (250km/h), reducing the travel time between the two cities to less than four hours.

Now, 15 years later, Russia is ready to improve on that even further. Putin has announced a new railway that will cut travel time in half between the two cities, using new locomotives made domestically by transportation firm Sinara. The new trains are reportedly designed to reach speeds  of almost 250 miles per hour (400km/h).

Construction is said to have already started on the 421-mile (679km) line with 12 stations, which is being built by Russian firm VSM Two Capitals, and trains have been purchased. The project will cost more than $25 billion (£20bn) and is being funded by a mix of public and private money.

Completion of the new line is scheduled for 2028, and there’s a possibility it may be expanded to Minsk in Belarus. Russia’s rail agency has set a goal to have at least 4,350 miles (7,000km) of high-speed rail by 2035.

It’s estimated that 44 million tonnes of freight cross the Western Alps annually, and 90% of that travels by road. A new rail line connecting Lyon in France and Turin in Italy aims to reduce this traffic and transport at least half of the freight by rail when completed in 2033. The 168-mile (270km) cross-border connection will also serve passenger rail services.

However, before a million or more lorries per year can be taken off Alpine roads, two tubes – each more than 35 miles (57.5km) long – must be mined through the mountains.

Construction is underway and involves connecting newly built and existing tracks to create the line. However, the bulk of the work involves excavating 100 miles (162km) of tunnels using both conventional blasting and mechanised methods. Work from the Italian side started in 2021, while work on the French side started in 2022.

The project has already faced a multitude of challenges due to its depth, not to mention the complex geology across its 12 worksites. The total cost is estimated at €25 billion ($26bn/£21bn), with Italy contributing 35%, France about 25% and the European Union 40% of the funds.

Since its opening in 1964, billions of people have ridden Japan’s Tokaido Shinkansen bullet train, which travels at speeds as fast as 177 miles per hour (285km/h). However, the nation’s rail agency is eager to make use of 'maglev' technology – where massive magnetic forces are used to create levitation – to reduce journey times even further.

The Chuo Shinkansen train will link Tokyo to Osaka via Nagoya, travelling at speeds of up to 310 miles per hour (500km/h). In order to reach these incredible speeds, 80% of the maglev line will run on tracks underground, bypassing dense urban environments and mountainous terrain. 

This ambitious project got the green light in 2009, and construction started five years later. Initially, the Chuo Shinkansen line between Tokyo and Nagoya was expected to be operational by 2027. However, it's now been pushed back to 2034 following a variety of issues, including stoppages due to depleted water supply in wells along the route, as well as lawsuits against the project from residents impacted by the construction.

Criticism has been levelled at the line's environmental impact, as well as its cost, which has skyrocketed to more than 9 trillion yen ($60.4bn/£48bn).

China announced a plan in 2016 to grow its high-speed rail network with a new programme of works called Eight Vertical and Eight Horizontal. As you may or may not guess from the name, these new or expanded lines comprise 16 new north-south and east-west rail connections with the goal of creating a total network of 23,600 miles (38,000km) by 2025.

One of these projects is the 1,300-mile-long (2,100km) Shanghai-Chongqing-Chengdu corridor, which parallels an existing east-to-west line but will offer substantially faster train travel. Able to reach speeds of 217 miles per hour (350km/h), the journey between Shanghai and Chongqing will drop from 10 hours and 42 minutes to five hours and 48 minutes.

The project has been divided into several sections, many of which are underway, with construction starting on the Hefei-Wuhan and the Yichang-Fuling sections in 2024. According to local media reports, the two projects employ more than 6,000 workers on the two lines, which require building hundreds of miles of bridges.

The entire 1,300-mile (2,100km) Shanghai-Chongqing-Chengdu project is expected to cost 560 billion yuan ($77bn/£61bn) once completed in 2030.

With north-to-south rail services in England at full capacity, the UK’s Department for Transport announced High Speed 2 (HS2) in 2010. This ambitious programme would create a new Y-shaped high-speed rail service from London to Manchester and Leeds, via Birmingham, built in three phases.  

In 2012, it was estimated that the first 140 miles (225km) from London to Birmingham –which will include four new stations, 32 miles (51km) of tunnels and 179 bridges – would cost £20.5 billion ($26bn) and open in 2026.

Project costs spiralled out of control before construction work formally started in 2020, the same year a review of the project revealed the price of the new railway could run to as much as £106 billion ($135bn). Inflation is partly to blame for the skyrocketing sum, but other factors, such as underestimating the costs of purchasing land and relocating utilities, are also at play. In a painfully ironic twist, a costly delay in awarding the construction contracts is partly due to a year-long pause to attempt to find ways to save time and money on the project.

In the end, the government cancelled both follow-along phases for the Y-shaped line in 2021 and 2023 in an attempt to reduce costs. However, there’s still no clear estimate of the total price tag. In summer 2024, the project told the Department of Transport to expect costs to range between £54 billion and £66 billion ($69bn–$84bn) but added this was only a rough calculation. The opening date is estimated at between 2029 and 2033.

Californian voters voiced their support for high-speed rail services in 2008. They approved a $9.95 billion (£7.8bn) bond measure to build an 800-mile (1,300km) high-speed rail system with as many as 24 stations. The 500-mile (805km) Phase 1 connection between San Francisco and Los Angeles would facilitate travel in under three hours, compared to a six-hour drive.

The project was slated to cost $33 billion (£26bn), though much like the UK’s HS2 project, this has ballooned while the actual rail line has shrunk...

Construction started in 2015, two years behind schedule. Governor Gavin Newsom then scaled back the project in 2019 to focus on a 171-mile (275km) 'starter line' within the Central Valley, from Merced to Bakersfield. One of the biggest hurdles for the project has been securing environmental planning permissions and land acquisitions along the route. Finances have been another challenge, with the COVID-19 pandemic and inflation creating supply chain issues, as well as President Trump freezing federal funding during his first term.

The California High-Speed Rail Authority’s (CHSRA) most recent report revealed the project costs are now $88-$128 billion (£69bn–£101bn), and the line is unlikely to be finished by 2033. However, the authority also highlights that $22 billion (£17bn) in economic activity has been generated by the project, which has only spent $13 billion (£10bn) to date.

Meanwhile, now back in office, President Trump’s administration has announced it's looking into the rail project to determine if nearly $4 billion (£3bn) of federal funding allocated to the project is being misspent. Watch this space...

Now discover 12 of the costliest cargoes in history