"The lights will only operate when traffic queues activate the metering," he said.
"When this happens, the lights will turn orange then red to stop the vehicles, allowing SH2 city-bound traffic to enter the roundabout."
Give-way rules will still apply when entering the roundabout.
The project cost $370,000 and would be trialled for up to 18 months.
Richard Fenn's home overlooks the Elizabeth St lights and the longtime resident questioned the role of traffic lights at a roundabout.
"We have lived here for 17 years. When we first arrived there were very few cars, now they can get backed up along Elizabeth St from Cameron Rd," he said.
"Traffic lights don't eliminate traffic flow."
An employee at Jetts Tauranga, who did not wish to be named, believed the traffic lights could help to improve congestion at the roundabout.
"Having it monitored could work. I have seen it work in other areas in Tauranga, like at Brookfield," he said.
A worker at TyreMaster on the corner Elizabeth and Glasgow Sts said trying to get on to Elizabeth St in peak traffic after work was tricky.
"Elizabeth St is the worst," he said. "Trying to get onto Elizabeth St was a nightmare."
Meanwhile, roundabout metering at State Highway 29A on Barkes Corner had been operating since December 10.
Campbell said early indications were positive, particularly in the evening peak.
"We are monitoring the performance of the roundabout metering at SH29A Barkes Corner, and now that schools are back we will analyse the performance and impact on travel times in more detail," he said.
The cost of the Barkes Corner roundabout metering was $830,000 and will also be trialled for up to 18 months. If successful, the lights will be permanent.
Customer services worker at Hirepool on Pyes Pa Rd, Daniel Poole, said the lights had been working to help improve traffic flow.
"There has been no serious crashes. I think it is working quite well."
The principals of Aquinas College and Greenpark School say they have not had any feedback regarding how the newly controlled roundabout has impacted traffic.
Tauranga City Council acting transportation manager Phil Consedine said the council was supportive of improvements to junctions between the state highways and arterial roads.
"We expect to see a reduction in traffic congestion at these locations."