Cheung, 57, was pleasantly surprised to find that a number of fellow enthusiasts were young people. 'Because trams are slow I thought young people might not like them as much as middle-aged folks,' he says.

Younger tram buffs have injected fresh energy into the hobby. Because model streetcars and paraphernalia are scarce compared to trains or cars, Eric Lee Tsun-lung began making his own a decade ago, using everyday material such as cardboard and toothpicks.

The 10 models that he assembled, which will also feature in the exhibition, reveal his vision of how trams might develop.

'I like the classic look of trams, but I always imagine how they would evolve in the future,' says Lee, 25. Among his prize models is a cafe tram offering beverages and snacks for passengers.

The financial services executive has loved trams since he was a toddler, when streetcar clatter and bells soothed him. 'My mother said I'd stop crying once I heard the tram sounds,' Lee says.

Trams still help lull Lee to sleep: he has built a miniature town in his bedroom where trams wind past model houses and parks.

Physics student Willie Yip Tsan-pong has brought tram buffs into the internet age. The 22-year-old has developed a computer game simulating an actual journey, allowing players to operate a tram from the Happy Valley terminus to Bowrington Road in Causeway Bay.

To create the detailed three-dimensional scenes along the route, Yip had to take at least three photos of most buildings from different angles, and at roughly the same time of day to ensure the lighting was consistent. This has meant countless tram journeys over eight years, but the cheap fare made it affordable. 'I definitely got to know my neighbourhood better because of the project,' he says.

Inspired to trawl through libraries for old photos and documents about trams, Yip says he was amazed to learn that Hong Kong's 163 trams comprise the largest double-decker fleet in the world still in operation.

Although the operation hasn't changed much since trams began rattling along Hong Kong Island in 1904, the city's rapid development has transformed scenes along the route, says historian Cheng Po-hung. 'The trams used to run parallel to the original shoreline, but continuous reclamation meant they were pushed farther and farther inland,' says Cheng, a regular speaker on tram tours.

Retired tram driver Ho Chi-kin says his regular route between Causeway Bay and Kennedy Town used to be much more pleasant before development led to tracks being enclosed by tower blocks.

'It was quite cool with breezes coming through the windows when I first drove trams,' Ho says. 'Now the harbour front is blocked by high-rises. The increasing number of private cars and heat generated by air conditioning make roads even hotter.'

Even so, enthusiasts find tram rides offer an inimitable way to experience the city.

Heritage conservation writer Roger Ho Yao-sheng says trams allow him to observe street life, from courting young couples to stall vendors and busy shoppers in different districts.

'Taking buses is more comfortable, but people either take naps or watch TV on buses. Human interaction is minimal,' says Ho. 'Tram rides provide more chance for people to strike up a conversation.'

Although they haven't set up a club, many enthusiasts meet through tram tours and at specialist shops, where they trade stories and collectables.

Cheung, for instance, acquired a prized set of tram tickets issued during the Japanese invasion through a chance meeting with British graphic designer Redge Solley at an antique shop about 15 years ago. They got to talking and decided to meet again to swap some pieces.

In an exchange for a HK$500 banknote from the 1950s that Cheung had, Solley brought an album of postcards for him to choose from. Just as they were about to settle the deal, Cheung spotted the tickets in the back of the album. 'I was thrilled,' Cheung says. 'Redge was so generous that he gave them to me because he knew I like trams so much.'

So when Solley was commissioned to design a special stamp to mark the centenary of Hong Kong Tramways a few years ago, Cheung lent the designer his memorabilia as reference material. The set of stamps, which depicted five important stages in the development of the city's tram system, was a sell-out.

But with French company Veolia Transport taking a controlling stake in Hong Kong Tramways in April, some enthusiasts are apprehensive what changes the new owners might introduce to boost profits.

'We hope the new management will consult the public when making changes,' Cheung says. 'Hong Kong people have an emotional tie with trams because they have been with us for a long time.'

Tramways new managing director Bruno Charrade says they won't be making any revolutionary changes. The idea is to gradually improve the trams' technical and operational systems and customer service while preserving their nostalgic image. Any future alterations will be introduced only after an extensive survey to gauge public opinion.

Tram buffs will be relieved.

Hong Kong Tram Exhibition; tomorrow to Jun 21; noon-9pm, 1/F Plaza Hollywood (3 Lung Poon St, Diamond Hill). Alan Cheung will also give talks on tram history on Jun 13, 20 (3pm, 5pm), and Jun 14, 21 (1pm, 5pm). Inquiries: 2118 8811