In widespread markets, from North America to the Middle East, various forms of rail systems are coming into a major growth phase -- in some cases projected to double by 2022. Some regions, including parts of Africa, will involve tremendous infrastructure efforts -- building track, carriages, and support structures. Other places, like the United States, will see world-leading demand for light and commuter rail systems. Many companies and governments will be involved, but here are a few ways to tap into the massive demand approaching the rail industry.

Back from the fringe
As reported in the International Railway Journal, African infrastructure requirements are turning increasingly to rail systems as a way to handle the growing interest in African mineral deposits, as well as the burgeoning urban populations. A German consulting service released a survey estimating that the rail network will grow by more than 14,000 route kilometers by 2017.

Asia-Pacific rail network growth and enhancement is substantial as well, with 120,000 route km of track in China alone by 2020. Europe will be replacing more than 10,000 locomotives and nearly 2,000 railcars between 2015 and 2022.

While Latin American as a whole is growing its rail network, Brazil is one of the biggest contributors. The nation has plans to expand 12,000 route km of track through this year alone. There is a tremendous amount of freight rail throughout the nation and in Latin America, but passenger rail leaves significant opportunity.

This article could provide stats about large government-funded network expansions from every corner of the earth, but you get the point: Significant opportunities abound in the rail industry.

How to tap in
Investors have long been fans of domestic and North American rail network companies such as Union Pacific (NYSE:UNP). The freight rail company has been on a nearly vertical trajectory since the recession, up more than 200%, along with regular dividend increases. The company just recently announced that it will again boost its payout by more than 14%. Union Pacific will continue to grow, as freight rail in the U.S. is projected to grow further, along with infrastructure improvements, yet it still trades at under 15 times earnings.

 There are other, more indirect methods of tapping into the humongous international growth. Siemens (NASDAQOTH:SIEGY), for example, was recently awarded part of a 22 billion euro contract from Saudi Arabia as part of a new six-line metro system buildout. Back in the U.K., a nation where many, many cars, tracks, and locomotives are set to be replaced, Siemens was awarded a contract for more than 1,100 new cars, to be delivered to London starting in 2016. The deal is worth 1.8 billion euros -- or nearly $2.4 billion.

There are plenty of other ways to tap into the rail boom, some more risky than others. But these two plays, one American and one European, offer safer bets that will no doubt benefit from the re-emergence of rail as a transportation linchpin.

Fool contributor Michael Lewis and The Motley Fool have no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.