RiverCity Motorway Group said on Friday that the toll reduction it implemented beginning Monday this week resulted to a 12 percent boost on Clem7 tunnel as about 28,415 vehicles passed through the 6.8-kilometre road on Thursday.

The seemingly unpopular Brisbane tunnel only saw an average of 22,000 to 25,000 vehicles each day since its opening in March, which is more than 50 percent below from its projected traffic prior to its initial operation.

RiverCity said that the Thursday figures were so far the highest number of daily trips on Clem7 since tolling was commenced in April and an improvement of 12.8 percent as compared to the June workday average of 25,192.

Under the toll discount, which will be in effect until the end of September, cars need only to pay $2 from the previous $2.95 while heavy trucks would be tolled $5.30, smaller trucks at $3 and motor bikes at $1.

Previous charges for the three types of vehicles were $7.82, $4.43 and $1.48 respectively.

Premier Anna Bligh said that the government is unlikely to take equity on the fledgling tunnel but she did not rule out the possibility that it could eventually happen.

Ms Bligh said that state government has not been presented with the idea of taking equity on the tunnel but she gave assurance that the government is ready to study such proposal if something like that would be pushed in the future.

Apparently picking from the encouraging news, RiverCity shares gained up to 43 percent on the share market and as of 1257 AEST on Friday, its stocks were trading at five cents, improving by 1.5 cents.