Despite being optimised for short runway operation, the RJ/146 has no reverse thrust, but relies entirely on some very substantial brakes. I did hear the whole main landing gear design is based on what was under the old De Havilland Comet 4 (designed in the same drawing office).
Besides stopping power, a further benefit of large and capable brakes is that they can pull the aircraft up without heating up near to limits, which allows the aircraft to depart again after a very short turnaround. Some types, such as the A320, have quite serviceable but nevertheless minimalist brakes, which require quite a holdover time to cool down before they can depart again (you may think the brakes are not an issue to take off but they need to be able to absorb any rejected takeoff at V1 speed).
The 146/RJ can of course get off again in a very short run, and not just at London City. I have departed in one from the old short runway 29 over on the north side of Dublin airport (shorter even than LCY), which I had previously imagined was confined to light aircraft.
Clever designers at Hatfield. Shame BAe trashed the whole commercial aircraft organisation.