RDA chairman R W Pemasiri said heavy congestion is seen on High Level Road, Baseline Road and from Malabe to the Parliament Junction.
"The new roads can be elevated on built on the ground," Pemasiri said.
"We will have a firm idea after the feasibility study is completed."
Roads around Sri Lanka's parliament in the administrative capital of Sri Jayewardenepura became heavily congested from early last year, residents say. Access to Colombo to fast developing areas like Malabe, falls through the area.
In 2010 Sri Lanka cut taxes on motor cars and monthly imports of cars alone are now around 4,000 to 5,000 units adding to the fleet compared to about 500 cars two years ago.
About 1,200 dual purpose vehicles are also registered compared to less than two hundred a few months ago.
Before that tax slashed or tax free cars were only available to state workers and the ruling class of elected legislators. Critics point out that even now ordinary second class citizens, pay higher taxes for