Quote from wikipedia
There are 55 lakh (5.5 million) registered vehicles in the city, which is highest in world among all cities (within municipal limits), while the Delhi metropolitan region (NCT Delhi) has 112 lakh (11.2 million) motor vehicles[1], again highest in the world among all metropolitan regions. This adds significantly to city's traffic and pollution woes. Delhi and NCR lose nearly 42 crore (420 million) man-hour every month while commuting between home and office through public transport, due to the traffic congestion.[2].
there are traffic lights in many places. But at times they do not work because of power failures or some other reason. There are many crossings where traffic lights are yet to be installed, but they are not major ones.
Oh and yes the traffic is hell. The worst I have encountered by car is travelling 3 kms (1.8 miles) in 3 hrs.