The NBIA ordered MJTA to modify its design to bring costs within the budget target and wants JBIC to approve new bidding on the modified design.
Deputy Prime Minister Chavalit Yongchaiyuth ordered the NBIA in March to cancel consideration of the design prepared by the Japanese group and to allow the NBIA to invite the nine former contractors who passed pre-qualifications for the earlier bidding to bid on the new design as modified by MJTA.
Then, in an unusual move, the NBIA allowed construction firms to bid on both designs, and in late September two successful bidders for the MJTA design -- one each for the terminal and concourse -- came in with bids totaling 8.8 billion baht over budget.
However, an NBIA source said mismanagement and the inability of an NBIA evaluation committee, comprising company and government officials, to examine the MJTA design led to overpricing.
A government source said the MJTA design, which specifies certain suppliers and materials, would give less room for kickbacks, while PCI's so-called ''fall-back design'' would allow more chances for the process to be corrupted.
Despite initially pushing for the second design, the NBIA has done an about-face and, after failing to renegotiate with the two lowest bidders to reduce the construction costs, requested the MJTA modify its design to meet the budget targets.
The MJTA submitted its modified design around mid-November, and the NBIA board is now seeking the JBIC's approval to redo bidding on the new design.
The MJTA design for an ultra-modern, glass-enclosed terminal building which analysts say will easily exceed the 45 billion baht (about $1.1 billion) budget allotted by the government.
Anant Soontornsiri, secretary general of the Association of Thai Engineering Consultants, said the MJTA design could be easily modified for low-cost construction, by revising some parts such as terminal concourse, interior or electrical equipment.