The trucks are more visible during the daytime, except that the drivers will never show any signal. (And you must watch for the absent signals - they are a greater threat). Only, you will often observe that the cleaner that sits next to the driver, will project his hand and wave hysterically. This is definitely not to be construed as a signal for a left turn. The waving is just an expression of physical relief on a hot day.
Occasionally you might see what looks like an UFO with blinking coloured lights and weird sounds emanating from within. This is an illuminated bus, full of happy pilgrims singing bhajans or hymns. This pilgrims go at breakneck speed, seeking contact with the Almighty, often meeting with success.