ENGINEERS investigating the June 2 collapse of a construction site hoist which killed 12 workers will this week dismantle its running tracks for tests to determine whether they contributed to the tragedy. Electrical and Mechanical Services Department Acting Chief Engineer, Stephen Chan Hung-cheung, said tests conducted in the past week on the actual lift cage had gone smoothly. ''I can't discuss details as there are legal implications since the Labour Department is likely to prosecute somebody in connection with the accident and we will be submitting our findings to the Coroner's Court,'' he said. ''However, we will be giving a preliminary report to the Labour Department within the week and they may issue details then.'' Japanese company Aoki, which is building on the Towngas site in Java Road, Quarry Bay, has monitored the tests. Aoki deputy director Berwyn Evans said the firm was committed to learning the reasons for the accident. ''We have been watching the tests every step of the way and will be on site when they dismantle the running rails,'' he said. ''At the moment we are not operating any other hoists on our sites throughout Hongkong. This is a pure coincidence and we certainly didn't pull hoists off our sites after the accident.'' He said the whole construction industry was waiting for the test results. ''We are all campaigning for safety and take it very seriously and are responding to the need to improve.''