The Department of Industry, which runs the science and technology centre, said visitor numbers had increased by 5 to 6 per cent so far this year.

This would mean an extra 21,500 to 25,800 people having fun at the centre in a 12-month period.

The bump in visitor numbers comes after the introduction of paid parking in the parliamentary triangle in October last year.

On Wednesday mother-of-two Lisa Postles said she was pleasantly surprised to find a car space at Questacon during the school holiday.

"I'd prefer to pay and have the availability," she said.

In previous years she had frustratingly driven "around and around" to secure a spot.

The new paid parking system aimed to turnover car parks more quickly and block public servants from hogging spaces throughout the day so tourists did not face the prospect of parking and walking long distances to national institutions.

Figures from the National Capital Authority show 5.34 per cent of all infringements in the parliamentary triangle - about $9200 a month - were slapped on windscreens in the small Questacon car park.

Parents need to be wary of parking limits when taking children to Questacon - a place where kids can easily become absorbed in activities as the purchased parking ticket outside expires.

Trent Russell from the National Capital Attractions Association said in the past there had been many negative comments on the online review site TripAdvisor about the lack of parking spots available at Questacon.

"Across the attractions [in the parliamentary triangle] I think there's been an increase in visitation," Mr Russell said.

He said money collected from the successful paid parking system should be going back to the NCA, so it can better maintain the parliamentary triangle, rather than the federal government.

Questacon received almost 430,000 visitors in 2013-14, not including children under four years of age and those who only visited the café, according to a recent report.