The availability test for TIAA MRT elevators and escalators, as stipulated in the contract, must be capable of continuous operation of at least 20 hours per day and 365 days per year under load. Each elevator/escalator must be capable of operating reliably and with a minimum of 99% availability (A). The availability (A) is calculated as below:
．MTBF: Mean time Between Failures
．MTTR: Mean time to Recovery
The average number of failures per elevator/escalator shall not exceed 15 times per 7,300 operating hours in the station. If the operating hours are less than 7,300 hours during the free maintenance period of one year, the average failure rate of each elevator/escalator should be estimated as the ratio of 15 faults occurring every 7,300 operating hours.
This availability test shall be conducted for a period of 12 months beginning within 90 days of the commercial operation day. The availability test for TIAA MRT elevators and escalators has been conducted since April, 2017. Before the 10th of each month, the supervising and manufacturing unit shall convene a review conference for the classification of the availability test faults with the manufacturers, operators and owners. In the conference, participants review the judgements of the faults classification in the previous month and calculate the availability of the equipment according to the requirements of the contract.
The availability reports are divided into quarterly reports, semi-annual reports, three quarterly reports and annual reports. The availability reports of equipment are submitted to the supervision unit respectively according to the above-mentioned timeframe for ratification. After the annual reports are submitted, the supervisory organization will convene the annual availability test implementation review meeting with the manufacturers, operators and owners to confirm that the equipment operation meets the contractual availability requirements.