This is what happen on Bangkok roads leading to New Year.
Every year after Christmas around 26th or 27th the tollways in Bangkok linking it to the upcountry will stop collecting toll fees this is to allow smooth movement of traffic as many people in Bangkok will leave the city to upcountry with home or for holidays. Will start collecting toll around 3rd of Jan.
So around 27th to 29th the highways leading vehicle away from Bangkok will experience traffic jam, come 30th all will be smooth.
Today is Monday, I drove along Ramintra Road and on Mondays at this time I drove (8am) it will be jam packed with vehicle but see here, smooth as silk
New Year and Songkrang are the best period to be in Bangkok, not just for good traffic but also for shopping and restaurants, not much queue.