Excessive vertical vibrations caused by uneven rail tracks and imperfect welding were to be blamed for the cracks found in the support brackets of a busy train underframe equipment, the Hong Kong Kowloon-Canton Railway Corporation (KCRC), said here Wednesday.

The Hong Kong Special Administrative Region (HKSAR) government also announced to establish a review panel to further investigate the rail problems that might put hundreds of passengers' life at risk.

The investigation report, released by KCRC on Wednesday, noted that the combination of the two main factors contributed to the occurrence of the cracks found on December 21 last year.

The probe found the force of vertical vibrations was excessive when a train was travelling at 70-90 kph over some sections of track, making the stress levels encountered by the support brackets far exceeding the original design limits by 100 percent.

Test findings showed a strong correlation between the occurrence of the minute undulations and a batch of rail supplied in 1998-99 for a track renewal program, which now makes up 36 percent of the East Rail line under KCRC, which operates a busy train line linking Hong Kong with the bordering Guangdong Province.

The second factor is attributed to imperfections in the welding of some of the underframe mounting brackets which the train manufacturer felt the mounting brackets were "adequate."

KCRC Chairman Michael Tien said the board has considered and accepted the report.

"I have always remained confident that passenger safety was not at risk during and after the incident," Tien said, "and the investigation confirms this key finding in the report."

Tien said the report also confirms that the KCRC staff involved in handling the December 21 incident and their subsequent actions, performed their duties with due diligence and in a "professional and competent" manner.

"The report also confirms that KCRC maintenance staff have been following closely the manufacturer's maintenance guidelines, and there is no evidence to show that lack of due diligence to the occurrence of cracks on their part is a contributory factor," he said.

Noting it is not practicable to remove the minute undulations along the rail top due to the limitations of the existing maintenance equipment, the board, however, has approved a series of improvements to reinforce and upgrade all underframe equipment mounting brackets.

The KCRC board has also promised to suspend the systems of the entire fleet of all 348 mid-life refurbished train cars and replace the critical sections of rail that have exacerbated the vertical vibrations.

The board said these measures will enable mid-life refurbished train cars to withstand the measured level of vertical vibration. All of these works are targeted for completion next year.

While findings of the investigation and independent reviews by specialist consultants show KCRC maintenance standards and procedures have not been a contributory factor in the occurrence of cracks in the underframe equipment mounting brackets, maintenance procedures for the mid-life refurbished trains will be strengthened, according to the KCRC board.

After the release of the KCRC report, Secretary for the Environment, Transport and Works Sarah Liao said the HKSAR government has formed a review panel to study the reporting of East Rail incidents and examine the existing reporting mechanism and propose improvements.

Noting the Government has received the root-cause report, Liao said the experts will study it in detail to establish firmly that the cause has the basis of scientific support and the proposed measures are effective.

A report will be submitted by the review panel in June to pinpoint the responsibility and liability issues relating to the incidents, Liao said, adding an expert group comprising members from the Railway Inspectorate, the Highways and Electrical and Mechanical Services Departments, as well as an international expert, has been reviewing East Rail problems with underframe equipment.

Source: Xinhua