London’s Heathrow airport, which has operated its two runways close to capacity since the start of the decade, managed to squeeze in 2.3 million additional passengers last year as airlines deployed bigger planes and carried more people per flight.

The traveler tally at the home base of British Airways increased 3.1 percent to 78 million even as the number of aircraft movements rose just 0.2 percent, Heathrow Airport Ltd. said in a statement Thursday. Airlines have upgauged to larger jets such as Airbus SE’s A380 superjumbo and the latest A350 while also squeezing more seats onto existing models.

The passenger surge shows Heathrow is finding ways of accommodating more customers as it awaits construction of a 16 billion-pound ($22 billion) third runway that will lift annual capacity to 135 million flyers. Backed by the government in 2016, the new strip still faces a number of hurdles and isn’t due to open until 2025.

The airport was able to add only 800 new flights or just over two per day by optimizing takeoff and landing patterns.

Most of the jump in passengers came from carriers upgauging to bigger planes including the A380, which typically operates 25 departures a day from Heathrow with nine carriers, the most at any terminal apart from Dubai. British Airways has 12 superjumbos and is the biggest operator of Boeing Co.’s venerable 747 with 36 aircraft, some of which it plans to retain until 2024.

Airlines are also upscaling to bigger narrow-body jets, and others have pursued “densification,” in which aircraft capacity is increased either through boosting the proportion of economy berths or removing bulkheads, moving toilets and adding thinner seats to create room for extra passengers.

Heathrow’s load factor, or seat-occupancy level, also increased by 2.6 percentage points to more than 78 percent, showing that flights are operating with fewer vacant berths.

The hub’s fastest-growing passenger markets were the Middle East, Latin America and Asia Pacific, though Europe and North America accounted for the most people. It also reported a 10 percent surge in cargo volumes to 1.7 million metric tons, led by growth from the U.S. and East Asia.

Runway Cost

As the U.K. prepares to exit the European Union, Heathrow Chief Executive Officer John Holland-Kaye said the record passenger tally shows the airport is “helping to strengthen the British economy as the country seeks to redefine its role in the world.” Travel demand has been indirectly encouraged by Brexit, with the weaker pound helping to boost inbound customer numbers.

The airport will next week publish plans to slash the cost of the third runway by 2 billion pounds, with proposals set to include the staggered construction of new terminals, retaining more existing buildings, and sloping the new strip so that there’s no need to divert the M25 motorway into a costly tunnel.

Manchester Airport, Britain’s third-busiest, boosted passenger numbers 8.5 percent last year to 27.8 million, with London Stansted, the No. 4 and also owned by Manchester Airports Group, lifting its tally 6.5 percent to 25.9 million, according to a statement Thursday. London Gatwick, Heathrow’s closest U.K. rival, will report figures tomorrow, as will Aeroports de Paris, owner of Charles de Gaulle airport, which ranked second to the U.K. hub in Europe in 2016.