Engineering in Bombay Locals

The Bombay locals are 9 or 12 compartment magnets on rails. They sweep up millions of iron filings from the platforms every three or seven minutes and dislodge them at places they wish to get off. For a boy or a girl of any age, magnets are wondrous things. It is the potential in them, the magnetic potential. The boys and girls are magnetic dipoles, the yin and yang of cosmic energy, mangetic energy if you will.

Traffic on the foot over bridge at Dadar railway station is an incredibly complex example of fluid dynamics. Near the walls of the bridge the liquid velocity is zero, as people either hang onto the railings, waiting for potential soul mates to arrive or are obstructed from moving by the hangers on. Velocity is the highest at the centre. People flow in seven or eight discernible layers in the tube, each layer's flow runs counter to the neighbouring layer's direction. The people layers are miscible. The flow is set in due to the gradient, differences in concentration which in turn is a result of the differences in density at both ends, ie. the western and central lines. There is a major tapping near the booking office and pressure tappings in the form of a parallel, smaller foot over bridge connected to the central foot over bridge.