Maintenance is "critical work" that keeps the rail network going, Transport Minister Khaw Boon Wan wrote in a blog post yesterday.

The missive, titled Maintenance Isn't Sexy, spelt out the work done by maintenance staff at night after train services end. "They do a lot in those 3.5 hours," he said, explaining how checks are carried out on the almost 200 trains to be put in service the next morning and how any defective track components, such as rails, power supply and electrical cables, are changed.

The entire track system, tunnels and viaducts are also checked once every four to seven days.

"Maintenance also involves pre-planned servicing and testing of equipment that is taken out of service temporarily, and major equipment or system overhauls," he said, adding that this is usually done in depot workshops or by system suppliers or manufacturers.

He wrote: "No one appreciates it until something goes wrong. Sexy or not, maintenance is the most valuable work we need to do well, to keep a complex system humming.

"It is critical work because failure to spot and correct any telltale sign of equipment wear and tear can result in a major train service disruption." His comments come in the wake of the rail failure on July 7 that crippled the North-South and East-West lines, affecting more than 400,000 passengers. SMRT was fined a record $5.4 million for the incident, which arose because of inadequate maintenance.

In his post, Mr Khaw said that more manpower will be needed for the rail industry. "As our rail network grows, and we run more trains and trips, we need many more engineers and technical staff to get all this maintenance done properly. We are still short of skilled staff."