Bangalore to Chennai Road condition and route

We had to travel to Chennai in Sept 2015 for some personal work. We generally take the train or Volvo buses, this time we decided to drive in our Swift ZXI car. We started off in morning at around 8:30 AM.  Our house is close to NICE road junction so we are quickly able to escape the city traffic. We were on Hosur road by 9:00 AM and were cruising out of the city. It was a public holiday so we did not get much traffic on our way out of Bangalore otherwise it would have been 15 to 20 mins extra in trying to reach Hosur. 
Route : Bangalore >> Hosur road >> Hosur >> Krishagiri >> Vellore >> Arcot >> Chennai
Near the Hosur border there is some congestion due to RTO check post. I wish they can clear up the congestion by making some parking on the side. Once you clear that the road is quite good upto Krishnagiri. From there we were supposed to take left Chennai, for some reason we missed the sign board and went 10 kms ahead and had to come back and take the left to chennai.
The roads upto Arcot are excellent and quite scenic. There are all kinds of mountain formation. Stone mountains, Stones and trees and even fully green mountains with icing of clouds. You will feel like stopping at many places and taking a picture. If it drizzles or cloudy its even better drive.  This stretch is an outing by itself. Lush green mountains close to AH45 highway are treat to watch.
Ambur a place famous for biryanis is also on the way. If you like Ambur Biryani ( amazing flavor) you may want to stop here for lunch. Star biryani is the main hotel, but most hotels serve equally good biryani. After the biryani since the weather was hot we sipped a cool ice cream before we started the onward journey to Chennai.
Around 100 kms before chennai the road started getting bad. The potholes were filled unevenly and since it was afternoon time and hot the last 90 kms or so was quite hard for us. The car was on full AC and speed had reduced to 60 to 90 kms max.  As you close in to chennai the traffic will keep getting worse. Its best to assume that last 100 kms would take atleast 2 hours.  
If you have a GPS in the car its quite cool, else you will need a navigator once you are in Chennai. We reached there approx 2:30 PM , with 40 mins of break in between . We got less traffic in chennai due to bank holiday and hence probably made it 30 mins early and saved lot of energy.