Since 1963, Lego pieces have been manufactured from a strong, resilient plastic known as acrylonitrile butadiene styrene (ABS). As of September 2008, Lego engineers use the NX CAD/CAM/CAE PLM software suite to model the elements. The software allows the parts to be optimised by way of mould flow and stress analysis. Prototype moulds are sometimes built before the design is committed to mass production. The ABS plastic is heated to 232 °C (450 °F) until it reaches a dough-like consistency. It is then injected into the moulds at pressures between 25 and 150 tonnes, and takes approximately 15 seconds to cool. The moulds are permitted a tolerance of up to twenty micrometres, to ensure the bricks remain connected. Human inspectors check the output of the moulds, to eliminate significant variations in colour or thickness. According to the Lego Group, about eighteen bricks out of every million fail to meet the standard required. Lego factories recycle all but about 1 percent of their plastic waste from the manufacturing process. If the plastic cannot be re-used in Lego bricks, it is processed and sold on to industries that can make use of it. Lego has a self-imposed 2030 deadline to find a more eco-friendly alternative to the ABS plastic it currently uses in its bricks.
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 intelligent brick can be programmed using official software available for Windows and Mac computers, and is downloaded onto the brick via Bluetooth or a USB cable. There are also several unofficial programs and compatible programming languages that have been made to work with the brick, and many books have been written to support this community.
LEGO CITY has some recurring themes that can get old after a while and obviously are meant for younger LEGO fans. The Fire and Police themes within CITY quickly come to mind as it seems like they have a new run each year. The Airport theme is one of those that doesn't quite occur every year. The last airport set was released in 2010 and was set #3182. This year (2016) another airport was released. #60104, Airport Passenger Terminal, was released on 1 August 2016 in the US. It costs $99.99 in the US and contains 694 pieces or $0.144 per piece. I picked the set up from Amazon at 20% off or $80 ($0.115 per piece). Yay sales! Onto the review...