THE number of crane operators has nearly doubled in the past year, but construction projects may still be delayed as many new hires do not have the experience needed for complex jobs.

And while the rules allow for four foreign hires to every one local hire today, they will be tightened to a ratio of two to one by 2017, and that could worsen the crunch, said Singapore Crane Association chairman Alan Chan.

There are about 6,000 crane operators today, almost twice the 3,600 reported by National Development Minister Khaw Boon Wan in a blog post he wrote last year about the manpower shortage for building new Housing Board flats.

But while the increase in operator numbers is encouraging, construction companies told The Straits Times a "gaping" need remains for workers with at least five years' experience, an industry standard.

This is because high-risk projects, particularly those in populated areas, require "much more careful handling", said Mr Belvin Tan, 47, safety manager of Yau Lee Construction. It will take time to bring the new pool of hires up to standard, he added.

The need is made even more pressing by the ageing pool of operators, more than 40 per cent of whom are above the age of 50.

Many will find it hard to continue working with increasing age and its impact on eyesight, and chronic illnesses like heart conditions and high blood pressure, said Mr Chan.

Though the association does not have concrete figures, Mr Chan said the attrition rate due to health conditions is "quite high".

Ageing crane operators may also find it harder to renew their Class 5 driving licences needed to operate mobile cranes after the age of 65, which would further shrink the pool.

Though the Monetary Authority of Singapore lowered its forecast for the growth of the construction sector earlier this month after an industry poll, insiders say about 800 to 1,200 more crane operators are still needed.

The good news is that 1,500 people attended the second annual crane carnival held on Sunday and 226 people registered their interest in joining the profession.

Last year, fewer than 200 people out of 800 who attended the carnival signed up for interviews with crane renting companies and the Building and Construction Authority's Crane Apprenticeship Programme.

Until now, Singaporeans have not been willing to step into the breach, because of the tough working environment of construction sites, society's perception of crane operators as manual labourers and safety concerns.

"But today's operators work in a high-tech environment with air-conditioned cabins and touchscreens," said Mr Chan.

Something else that might help the search for qualified operators is a registry and accreditation system, said Huationg general manager Jimmy Chua, 54.

The registry would include details on licensed operators' training records and the number of hours they have worked on sites.

This could help change the mindset that a crane operator who has held a licence longer is more experienced.

According to Mr Chua, there are some operators who have fewer than five years' working experience who have clocked more hours than their seniors.