U.K. approves crucial third runway at London's Heathrow

(CNN) London's Heathrow airport is one step closer to getting a vital third runway.

The U.K. government issued its long-awaited decision on airport expansion on Tuesday, giving Heathrow the green light to build a third runway. The airport  which is operating at around 99% capacity welcomes about 75 million passengers a year, making it one of the world's busiest travel hubs. The new runway should nearly double its capacity to 138 million passengers by 2050.

The government's decision had been delayed for well over a decade due to political opposition and environmental concerns. Officials also considered a plan to expand London's Gatwick airport, which had lobbied for permission to add a runway. It's widely recognized that the U.K. needs to add airport capacity to expand trade and the nation's economy.

The lengthy delay in adding a third runway at Heathrow gave an advantage to cities like Dubai, which quickly expanded its airport capacity over the past few years and gained a reputation as a global hub.

Heathrow airport in London has been looking to build a third runway for years. It just got government approval to do so.

The government's runway decision has gained added significance in the wake of the U.K. Brexit referendum.

Many observers saw the U.K.'s vote to leave the European Union as a move towards protectionism and away from free trade. But the government hopes this decision will signal its commitment to expanding trade with global partners. James Stamp, a partner at KPMG who specializes in global aviation, told CNNMoney in advance of the government decision that the move "is going to send a message to the markets and the world that says the U.K. is open for business, we're committed to this, we're putting our money where our mouth is." The new Heathrow runway is expected to cost £17.6 billion ($21.5 billion), with taxpayers covering £5 billion of those costs. It's forecast to create nearly £150 billion in economic benefits by 2050.

But it's going to take a long time to build, with completion only expected in late 2025 at the earliest. Parliamentary discussions, planning and building could easily take a decade. A final parliamentary vote to approve the Heathrow expansion is expected in the next 18 months.