Many residents were taken aback by news that 14 passengers were injured when a west-bound tram toppled over in Central early on Thursday morning.

With a speed limit of 50 kilometers per hour, and guided by a tram track running on an exclusive carriageway, tram cars are generally perceived to be the safest motorized traffic tool on earth. Indeed, they are, according to statistics.

Few would have imagined the scene of a tram tipping over completely and lying flat on the ground. The silver lining, if we are thoughtful enough to see it, is that the mishap happened in the small hours when traffic was light and passengers were much fewer than in the daytime.

It could have been a lot worse if the accident had happened during the day when traffic is heavy and many of the passengers are elderly people who are much more vulnerable to accident injuries. Many elderly people, who don't have a tight schedule to meet as the young people do, prefer riding a tram rather than a bus whenever they have the choice. This is not only because a tram ride costs far less than a bus ride but because it offers them a chance to refresh the old memories of their heyday as the tram strolls along the old streets downtown.

The accident, in effect, has overturned the long-held perception of Hong Kong residents that trams are safe to ride. It also raised a question: Could it be that complacency has played a part in triggering the wee-hours accident?

While it is too early to jump to a conclusion as the police are still investigating the real causes, there have been suggestions that it could be a speed-related accident.

The facts - that the scene of accident is not known to be a traffic black spot and witnesses reported no collision with other vehicles - provide some support for such speculation. And operator Hong Kong Tramways had in effect excluded the possibility of mechanical breakdown when it said the tram had just gone through comprehensive maintenance and inspection on March 29, which had "ensured proper functioning".

Whatever causes the police may eventually find out, it is imperative that the tram operator wastes no time in enhancing safety measures, including carrying out more frequent mechanical maintenance and checkups on tram cars and providing more training to drivers, especially new drivers.

Trams might be less efficient than other means of transport. But they are one of the very few century-old icons of Hong Kong and have proved to be a tourist attraction. Hong Kong is luckily among the few cities in the world that still operate trams. There is every reason we should try our best to ensure their efficient and safe operation.

(HK Edition 04/07/2017 page1)