Folks,
I had the pleasure of riding on the tram system in Nottingham yesterday into the city. We went from Wilkinson Street to Old Market Square, which is quite a hilly route. I found myself rather puzzled about the trams. How on earth do they go up and down the hills without slipping??
There are a couple of things that prevent the tram from slipping. The main thing is that the tram vehicles are very lightweight for rail vehicles (approximately 40 tonnes unloaded and up to 60 loaded) and have 8 out of the 12 wheels driven.
The other thing that is used to prevent slipping and sliding (they are two different things, the former is while taking power and the latter is while braking) is sand. Sanding is used extensively on tramways to increase adhesion and is applied in a number of scenarios. It is applied if the onboard computer detects sliding under braking or slippage when accelerating. It can also be applied manually by the driver using a button on the dashboard. In Nottingham you can hear this going on if you are sitting over the end most bogies on the older Incentro trams.
Even with these things there are still occasions when drivers will experience exceptionally low adhesion and it is these occasions where your skills and deft application of the driving-brake controller, sand and magnetic track brake is required.
Finally, glad you liked the tram system! We are very proud of it!
