THE city’s Metro operator has launched a major maintenance program to overhaul its air-conditioning system to provide commuters with a more comfortable experience this summer.

The Metro, which has experienced a rapid increase in passenger numbers, said it has prepared throughout the year for a scorching summer.

Stuffy carriages have long been the top complaint about the Metro network’s air-conditioning system, particularly during rush hours, when overloaded trains are common.

To resolve passenger complaints, since the end of last year the A/C system of the 14 Metro lines in the city has been inspected and improved where necessary. Lines 1, 2 and 3 have been given special attention.

Most A/C units of Line 1 were produced at least 10 years ago, for example, and some components are no longer in production. Last winter, maintenance workers set up an online database with profiles of more than 800 air-conditioning units on 53 trains, so as to track any A/C glitches on the line. For imported components that are no longer in production, the Metro operator has found domestically produced components.

In the spring, the Metro launched a “thorough inspection” on more than 8,000 A/C units covering over 4,000 carriages.

The Metro plans to set up a “big data center” this year to make maintenance work smarter. The new system will be able to collect real-time temperatures in carriages, so responses to complaints about air conditioning can be faster.

Metro staffers will also patrol trains more frequently to react to A/C complaints quicker.