Trial run for heavy and wide components on TAO summit access road

Most important events in construction phase of TAO project are construction of the telescope, installation of mirror coating chamber to the ceiling of support building, and installation of primary mirror to the telescope. To accomplish these tasks, these components have to be transported to the 5,640m summit of Cerro Chajnantor. They are the largest structures of TAO facility both in size and weight which must be handled very delicately. Then this trial run is one of the important milestones in TAO project.

As failure is not acceptable in actual transportation, certainty and safety must be confirmed in advance with trial run using dummy cargo and weight. Before the trial run, a careful preliminary check of road condition is also conducted. There are many items to be checked: ensure of maximum road width (7.5m), securing the turning radius in the curves to available the trailer to turn, critical bumps against vibration, enough power of the trailer, enough space to ensure the safety of watchdogger. There are more than 30 checkpoints of the road width from 5,000m yard to the summit. They were measured and checked by hand one by one. Areas of concern will be widen the road or be marked to adjust the height of the banks before trial run.

▲(left) Scene of measuring the road. (right) Checking the stones to be removed.

After the preliminary checking and road repair, the trial run was carried out from March 19 to 21, 2024 (for 3 days). Two types of truck (trailer) was tested. The one is a low bed trailer and the one is a module trailer which can carry heavy loads with multiple axles. The former carries the center section of the telescope and the elevation disk. The latter carries the coating chamber, the primary mirror cell, and the primary mirror (transportation box). Each trailer loading the weights of maximum weight (28t and 42t) was checked its power. And by loading a dummy that imitates the maximum external shape to be loaded, it was checked for interference with the road and the mountain.

On the first day of the trial run, the low bed trailer with 28t weight was tested. The speed for the trial run was set at about a walking pace on the curves and about 10 km/h on the straightaways for safety. We drove while checking the route at curves and removing some larger rocks, however as a result, we could complete the approximately 8-km route in less than one hour. On some hairpin turns, it was decided that it would be more efficient to maintain some speed to keep the trailer from getting stuck and to compensate for the power.

▲(left) trial run of the low bed trailer (right) the module trailer

On the second day, the low bed trailer with the dummy of the maximum external shape (5.5-m wide) was tested. We checked the state of interference at various locations on the road and confirmed that there were no problems. We continued a trial run of the module trailer with the weight of 25t, which was to check the power of the module trailer. On the third day, we finally tested run with the dummy of the maximum weight of 42t and the maximum width of 7.2-m. Fortunately the weather was good and we could reach the summit only about an hour. Now we are ready to transport heavy and oversized items.

In the second half of 2024, the telescope and deposition-related items will be transported to the summit, installed in the enclosure and the operation building respectively. In the next year, the telescope will finally be ready for observation operations.

▲(left) Successfully arrived at the summit ! (right) Group photo of the trial run members