Hong Kong Suicides on Hong Kong's railway lines have declined by almost 60 per cent since platform screen doors were installed at underground train stations, an expert study said Sunday.

The number of people jumping to their deaths in front of trains annually has dropped from 10.2 to 4.4 in the five years since the barriers which run the length of platforms began to be put up.

Platform screen doors should now be installed at all railway stations "without any delay", said the University of Hong Kong academics who carried out the study.

However, the MTR Corporation said it would take four more years to complete the fitting of the barriers at remaining stations and indicated it had no intention to speed up or expand the project.

Passengers have been paying a surcharge on every ticket since 2000 to pay for the scheme. Eight above-ground MTR stations and many more above-ground stations have no platform screen doors.

Railway operators claim that the work is taking a long time because of the need to avoid too much night time construction noise affecting residents living near stations.

Paul Yip Siu-fai, director of the university's Suicide Research and Prevention Centre and co-author of the study into railway suicides, said the findings should add urgency to the work.

"It is us, the passengers, who are paying for the safety doors, and tens of millions of (Hong Kong) dollars have already been collected since the surcharge was imposed. We think the work should therefore be done as quickly as possible."

The study found that the barriers were particularly effective in deterring psychotic patients from suicide as their decision to jump in front of a train was often sudden and impulsive.

MTR Corporation media relations manager James Tsui said installing the barriers would take until 2012 as it involved "highly complicated works including major modifications to the platform structure, ventilation system and earthing protection system." (dpa)