CONCERNED architectural experts have called on city authorities to take urgent measures to cut the glare reflected from the dazzling glass facades of Shanghai's high-rises and to check their overall safety.

Although the city is proud of its glamourous and ultra-modern skyline, the growing forest of steel and concrete skyscrapers with glass curtain walls is creating a threat to public safety.

Pedestrians and motorists are often blinded by the glare reflected from the multi-storeyed walls of glass and more tall glass-fronted office buildings are still going up along busy Huaihai Lu.

The problem became more acute after building inspectors detected other serious problems - apart from glare - associated with glass curtain-wall construction. A survey conducted by the Engineering and Materials Testing Technology Research Institute revealed major defects in glass curtain wall buildings.

"Nearly 10 per cent of the glass curtain walls in the city are unreliable and some are in a seriously dangerous condition," said Lu Jinlong, director of the Institute.

Results of the survey showed that 90 of the 931 inspected glass curtain walls have obvious defects.

Of the walls that most worried the experts, 76 showed glass with cracks or in danger of "self explosion"; 53 of them allowed water to penetrate; six had corroded aluminum frames; and, four had glass sections which were loosely held in place.

The survey began in March 1999 and covered all buildings with glass curtain walls completed by the end of 2001, including the Union Building - the first building in the city to be built with a glass curtain wall.

Most of the problem walls were built before 1997 when the city had not formulated technical standards or management regulations.

The survey also pointed out that more than half of the buildings inspected could not provide adequate information or had no information as to the starting and completion dates of the building or even the total surface area of the glass curtain walls which hindered their proper maintenance of the walls.

As glass is brittle and fragile, it poses an obvious danger to people in the streets below if a section of it cracks and drops.

Lu said such a case did occur when a glass curtain wall fell off a building at a construction site in Pudong several months ago.

"No media reported it but we insiders knew," Lu said. "Luckily, there were no casualties."

Based on the information collected in the survey, the research institute has set up a databank, the first of its kind in the country.

However, Lu said that as many buildings have not yet been included in the survey and many actual problems might have been concealed from the inspectors, the databank is far from being complete and a lot more work must be done to make it valid and keep it updated.

Shanghai has at least 1,000 tall buildings with large areas of glass curtain walls.

Although the city keeps abreast of world standards in terms of construction, management and maintenance after building work is completed, it still lags far behind in other areas, according to many architectural experts.

They said regular maintenance of buildings was far from being satisfactory and the most common form of maintenance adopted by comparatively responsible landlords was to clean the surface of the glass walls.

"The wide application of glass walls in building construction is a choice without real choice. No better substitute has been found or used yet in the country," said Zheng Shiling, from the Chinese Academy of Social Sciences and vice-president of the Architectural Society of China.

Tempered glass and laminated glass are favourites in modern construction in China and overseas because of their low cost and light weight and they make it easier for designers to create eye-catching buildings.

The Swiss architect Le Corbusier (l887-1965) was reported to take the lead in using large areas of glass on the facades of his buildings. It was introduced into China and has been in vogue since the 1970s.

Zheng said that connecting glass to a metal structure - as was done in the 88-floor Jinmao Tower in Pudong - was more stable than simply glueing glass to the building.

While experts have called for urgent steps to be taken to fix the problem, the city's construction supervisors - who supported the survey - have not yet been able to come up with definitive measures to ensure the city's glass curtain walls are kept safe.