Sydney or Melbourne: which airport upgrade is better for travellers?

The battle for Australia's ultimate airport experience is officially on.

Sydney and Melbourne are launching multibillion-dollar master plans to handle surging passenger numbers.

From liquid-in-bag security scanners to streamlined terminal transfers, both hubs promise a smoother journey.

But which city will actually deliver?

Sydney Airport's officially approved 2045 Master Plan eliminates the dreaded bus ride between split terminals for millions of passengers under a $6 billion precinct expansion.

Terminals 2 and 3 will merge into one huge domestic hub with swing gates allowing it to also handle short-haul international flights - like Bali and New Zealand.

This means many passengers will be able to walk straight to connecting gates.

T1 will still house the majority of international flights, but connections between this and T2/T3 will improve.

Advanced screening systems allowing passengers to leave liquids in carry-on bags, and upgraded baggage handling technology, are also under way, to manage higher volumes more quickly.

Transport for NSW is working to improve surrounding road connections, to make getting in and out of the airport by car smoother.

However, major construction doesn't begin until 2028, with swing gates arriving in the early 2030s.

Sydney Airport is expected to welcome more than 72 million passengers annually by 2045, including 36.4 million international passengers and 36.2 million domestic and regional passengers.

Melbourne's draft master plan focuses on a $4.5 billion international terminal expansion, adding five new gates, a sprawling Qantas lounge and a larger check-in and baggage hall.

The airport says the upgrade will allow faster check-ins, and state-of-the-art bag tracking technology will handle increased baggage demands.

A new drop-off and pick-up zone will open in October.

Qantas is supporting the plan, signing a 15-year agreement to support a third runway, which will allow new international flight routes - eliminating an extra hop to Sydney for many.

Melbourne has already upgraded its security screening technologies, allowing travellers to leave laptops and liquids in bags, and further check-in improvements are likely, as well as upgrades to the domestic terminals.

New transport links including road infrastructure and bus connections to nearby neighbourhoods, as well as rail access to the city via Sunshine, are planned.

The airport is expected to double its passengers over the coming 20 years, serving 75 million people a year by 2047.

Consumer expert Graeme Hughes, adjunct associate professor at Griffith Business School, says travellers should approach the plans with "hope and a healthy dose of suspicion".

"What Sydney flyers will actually feel soon is the quieter two hundred million dollar T2 refit already under way," Hughes tells Explore.

"New scanners mean the laptop and the sad, half-drunk water bottle can stay in your bag, and security lanes will move roughly twice as many people an hour."

Meanwhile, Melbourne's plan to expand a "hopelessly overcrowded" international terminal prioritises space and retail over queue reduction.

"The border is run by the Australian Border Force, a federal agency rather than the airport, so no quantity of shiny new marble conjures an extra officer at six in the morning," Hughes says.

He calls the biometric gates and smarter bag drop at both airports "good news" - but whether the queues will be shorter remains to be seen.

"So will these builds transform your next trip? They will make the airport calmer, roomier and rather nicer to loiter in, which is worth something," he says.

"Whether your bag turns up any faster is a matter for the scanners and the staff rosters, not the architects. Until then, the smartest travel hack remains the oldest one: get there early, and bring a book."