The firm building the flyover at the Kolombong Ring Road-Jalan Kolam intersection has installed a drain along the slope where drivers ascend from the City Mall area, following Saturday's flash flood.
A spokesman for the management said this should provide temporary relief for the problem created by the run-off.
"We hope the rainwater will be syphoned away faster, instead of pooling on the slope," he said.
"However, we will only be able to determine the effectiveness of this strategy when it next rains heavily."
He said the firm was working with the Public Works Department (PWD) and consultant to come up with a permanent solution. Asked the reasons for the problem, the said the design of the flyover was partly to blame.
"There is a little bend or curve at one point where the water collects.
"The road level at this section was designed at a higher level and the run-off tends to pond in the middle."
He said roadside drainage, including "weep holes" were also not part of the flyover's design.
"The rainwater is supposed to flow down the gradient and away from the flyover."
He was responding to complaints from two drivers, one from Penampang the other from Kolombong, about the traffic hazards posed by the water pooling on the flyover.
The spokesman said the firm received numerous complaints from motorists about this.
"We have had several meetings with PWD officers on how best to address this problem.
"The agency's director personally inspected the trouble spot on the flyover at the end February."
A Department spokesman said the agency was in the process of studying the problem.
"We hope to do away with the ponding once and for all once the other side of the flyover is completed by the middle of the year," he said. "In the meantime, our staff will keep an eye on this situation."
TONY of Penampang said accidents could easily occur at the place where the rain-water collected on the flyover.
"Drivers risk losing control and turning turtle when their vehicles impact on the pool, especially if they are speeding up the incline," he said.
"Alternatively, those behind might wind up colliding with oncoming traffic because of the water splashed onto their windscreen." He said he had noticed the water pooling on the flyover on and off since traffic was first diverted onto the structure in December.
JUDY of Kolombong bemoaned the jam on the flyover during a downpour on a recent Friday evening.
"Two Kancils broke down in the single lane going up the flyover from the City Mall area," she said.
"Apparently their engines had become water-logged at the section where the rain-water was ponding on the structure." She said it took her 45 minutes to travel from City Mall to the Lintas area that night.
Judy decried the congestion on the flyover as making a mockery of the structure.
"Isn't the flyover meant to ease the traffic jam which forms at the intersection?
"Instead, we now have a situation with bumper to bumper congestion on the flyover and the main roads at the bottom."