Retired traffic planner Joseph Yee said such a scheme can be challenging over a long stretch of highway, noting that there will be a period when signal lights on both ends will have to be red to facilitate a safe switchover.

"Nicoll Highway is short, so the all-red time was short," he said. "The longer a road is, the longer the all-red. And the longer the all-red, the more unacceptable it becomes for road users."