Traffic lights are to be switched off at some of Bristol city centre's busy road junctions.
The council wants to see whether it will cut down waiting times for drivers and still be safe for pedestrians and cyclists.
The lights at Union Street/Nelson Street/Broadmead will go off completely on 8 March and Broad Quay/Prince Street/Marsh Street on 22 March.
The trial will last about a month, a council spokeswoman said.
Similar trials have previously taken place in Portishead and Ealing but Bristol will become the first city in the country to undertake the trial.
Some members of the public expressed concerns about the switch-off including children walking to school.
A council spokeswoman said the sites were chosen out of a shortlist of seven after "careful risk assessments".
The other five failed for factors including concerns about high speeds, pedestrian safety and school crossings, she added.
The council will put bags over the lights and erect signs to inform drivers and pedestrians of the changes.
The impact of the switch-offs on traffic including buses, cyclists and pedestrians will be measured.
The spokeswoman added: "If all goes brilliantly, they may never go back on again but that's hugely dependent on public reaction."
The lights are expected to be switched back on after about a month of trialling, she said.