The infrastructure overhaul would substantially cut logistics costs, and the dual-track rail and high-speed train systems would facilitate travel, he said on Friday.
He was speaking as the 2-trillion-baht borrowing bill was being debated by the House of Representatives for the second day.
"In principle, the megaprojects development plans are good, and it is necessary to speed them up because they could help reduce the production costs of the private sector," said Mr Supavud, a veteran economist and investment banker.
"The transport sector now relies mainly on land transport, which is costly and means we must import a large amount of oil."
He said the development of rail systems, including the electric train network in Bangkok, would also reduce commuters' travelling costs.
A dual-track rail and high-speed train system would help cut transport cost across the country and enable Thailand to have more trade links with other countries.
Without these infrastructure development projects, Thailand’s trade competitiveness would be weakened due to high logistics costs, he said.
Mr Supavud said that if the government could ensure the economy grows by an average 5% annually, the ratio of public debt to gross domestic product (GDP) would fall, despite the high borrowing.
But if annual economic growth stalls at only 3%, this would be of major concern and would affect the public debt in the future.
Public debt currently is around 44% of GDP, well below the limit of 60% that the Finance Ministry enforces.
Commerce Minister Niwatthamrong Boonsongpaisan on Friday asked all sides to support the government's plan to overhaul the country's infrastructure.
The megaprojects would improve the confidence of both Thai and foreign investors and help ensure sustainable economic growth, he said.
"If the borrowing bill is approved by parliament the government can proceed with investing in megaproject developments, as planned, and the economy for this year and next will improve substantially," Mr Niwatthamrong said.
At the House meeting on Friday, the opposition Democrat Party disputed Section 4 of the loan bill, which authorises the finance minister to solely supervise the loan operations. It proposed that the role should be shared with the prime minister.
The government has said that of the 2 trillion baht, about 60% would be borrowed domestically and the rest would comprise bond issues in international markets. The money would be repaid over 50 years at a total cost including interest of about 5.1 trillion baht.
Puttipong Punnakan, a Democrat MP for Bangkok, said the borrowed money would be used on projects managed not only by the Finance Ministry but also the Transport Ministry. Therefore, the financing should be supervised by the premier, who has authority over both, he said.
Another reason for Premier Yingluck Shinawatra to oversee the loan bill is the very high risk of corruption associated with the colossal amount of money involved, said Mr Puttipong.
The House voted 289 to 103 in favour of Section 4 of the loan bill.
Chief government whip Amnuay Klungpa said lawmakers would try to wrap up the deliberation by today.
Most of the talk will be about sections 3 to 5 of the borrowing bill, which has a total of 19 sections, he said. The other parts of the bill will not take long to discuss.
Mr Amnuay added that the government would deliver its first-year performance report, a year behind schedule, this coming Tuesday, starting from 2pm.