3T Method - Mobile Access Tower Technical Update (Choice of Base Frames)

To ensure that there is always a metre of frame above each temporary deck to support the handrail braces during assembly/dismantling of the Tower, the correct base frames must be used. Here's how:

Choice of Base Frames - Odd Height Towers

If the deck height of your Tower will be an odd number of metres (i.e. 3,5,7,9 etc.), 2 metre frames should be used as base frames.

This will allow the first temporary deck to be fitted at 1 metre, leaving 1 metre (2 rungs) of frame height above it to attach the handrails, as shown.

All subsequent decks will be placed at 2 metre intervals above this deck, giving odd (3,5,7 metre etc.) deck heights

Note: The diagonal braces MUST be started in "Position 1" for this configuration to ensure that they give the greatest possible clearance as they pass the decks- see 'Diagonal Braces'

Choice of Base Frames - Even Height Towers

If the deck height of your Tower will be an even number of metres (i.e. 2,4,6,8 etc.), 1 metre frames should be used as base frames.

On the Eiger 500 tower shown here, the 1 metre base frames have 2 rungs, but the top of the first pair of diagonal braces fit onto the 3rd rung, and the top couplers of the Stabilisers fit between the 3rd and 4th rungs. A 2 metre frame must therefore be fitted on top of each 1 metre base frame (making hybrid 3 metre frames). The first two pairs of diagonal braces can then be fitted, followed by the first temporary deck at 2 metres (4th rung), and the appropriate stabilisers for the final height of the tower. This leaves 1 metre (2 rungs) of frame height above the first deck to attach the handrails (using either the 3T or AGR methods).

All subsequent decks will be placed at 2 metre intervals above this deck, giving even (4,6,8 metre etc.) deck heights

Note: The diagonal braces MUST be started in "Position 2 " for this configuration to ensure that they give the greatest possible clearance as they pass the decks- see 'Diagonal Braces'