Transforming the Museum Safely
The Auckland Museum is five years into its Future Museum transformation. Among many changes, new walkways have been built to make it easier to move around our historic building. Galleries have been revamped and will soon be classrooms and exhibition halls. These changes will help the Museum to tell great stories about Tāmaki Makaurau.
There has been a lot of construction needed to get us to this point. We've had to knock holes in walls, construct new ceilings and floors and install new air conditioning ducts and lighting systems. This sort of work creates a lot of vibration and these vibrations can be felt through walls, floors and support columns all across the Museum.
Vibrations in a museum
Vibrations can cause damage to objects found in museums in a number of ways. Firstly, vibrations can cause objects to move around on their shelves, potentially falling off. A museum in Manchester had some 'haunted' objects which appeared to move around by themselves on their shelves. It turned out, it was the vibrations of visitors' steps walking through the museum that caused the objects to turn on their shelves.
Vibrations can also cause loose paint flakes to become detached or old conservation repairs to re-break. Natural history objects such as spiders or butterflies with fragile components are also vulnerable to excessive movement from vibrations, as are collection objects with removable parts like clocks with pendulums or tea cups with saucers. The objects can become separated, or rub against each other, causing damage.
All of this means that we need to know what sorts of vibrations are being created, and how far they will travel, so that we can move collection objects out of the way or ensure they are safe where they are. This is why the museum has installed a vibration monitor (the MR3000) which enables us to test the vibrations caused by various types of construction, all across the museum building.
We have found that different sorts of equipment such as hammers, drills and concrete saws produce different types of vibrations. What a building is made from can also affect how vibrations are transmitted. For example, the northern half of the museum which was built in the 1920s contains brick and Portland stone. These materials respond different to the concrete mainly found in the southern half of the museum which was completed in 1960 and differently still to the more modern auditorium and event centre, which was constructed in 2006.
The vibrations monitor
We have tested to find out what our upper limit of acceptable vibrations are for our collection objects, which we've found is 2 mm/s. To ensure we don't exceed this limit, we have installed our vibration monitor next to the construction site. The monitor is pretty special in that it monitors all vibrations and if any exceed our limit it will email us an alarm! Then we stop the construction work and either protect the collection objects where they are or move them elsewhere.
In some situations we have had to remove collection objects from galleries, to be sure that they are safe. For example, one wall in the Māori Court backs onto the former Wild Child gallery. The display cases on this wall were full of taonga, which could have been damaged by the vibrations caused by drilling being done on the other side of the wall. Therefore we removed all of the taonga from these cases, and then returned them once the drilling was completed.
Other ways of protecting collection objects
In other areas we have been able to install foam to protect objects, so that they can remain in place. For example, when our new staff-room was being constructed, the vibrations travelled up into the rooms where we keep our collections behind the scenes. The Land Vertebrates and Entomology collections are too numerous and too delicate to move so they had to be protected where they are. This led to collections staff installing acoustic-dampening foam under all of the Entomology cabinets, and lining all of the shelves in the Land Vertebrates store with conservation-grade plastazote foam.
As the Future Museum programme moves forward, we will continue to monitor the vibrations caused by building works so we can give the best possible care to all of our collection objects.