In December 2012, the BBC's More or Less radio program asked the Open University's engineering department to determine "how many Lego bricks, stacked one on top of the other, it would take for the weight to destroy the bottom brick?" Using a hydraulic testing machine, the engineering department determined the average maximum force a 2×2 Lego brick can stand is 4,240 newtons; since an average 2×2 Lego brick has a mass of 1.152 grams (0.0406 oz), according to their calculations it would take a stack of 375,000 bricks to cause the bottom brick to collapse, which represents a stack 3,591 metres (11,781 ft) in height.
The first few bags build the small truck with carts that you see on airport runways. The truck has a "follow me" sign that I confess I have not seen at any airport. There is also a fueling tank and a rolling staircase that sits next to the plane to allow for boarding. Both the tank and the staircase are additional carts for the truck, though I am guessing not both at the same time.