When Sydney Airport closes for business tonight another group of workers will fire up.

Major construction work to upgrade airport security is now under way.

It’s a 24/7 job that officials promise will one day bring an end to check-in pain.

Sydney Airport’s terminal two is Australia’s busiest. The terminal has been left untouched for three decades but stage one of a $200 million makeover has begun.

The major upgrade is implementing government-mandated changes to a terminal built to accommodate just 8 million passengers a year in the days of Ansett.

There will be new lanes and more powerful CT bag scanning, meaning laptops and electronics will no longer have to be unpacked and unloaded into trays.

On completion, the airport promises passengers will move from curb to gate in just 15 minutes

The priority is keeping things moving to ultimately double domestic capacity.

The works have been planned to minimise disruption.

All the major makeover is happening behind closed doors, so 17 million passengers can continue to travel through each year

As the work progresses across the terminal there’ll be 55 new check-in desks, all self-serve.

The international terminal will also get revamped space for boarding airside buses as well as upgraded lounge areas.

Sydney Airport says it’s investing about $2 million a day, with work on the first stage of T2 to continue until the end of the year.