A chorus of wailing sirens and ringing bells will signal Samoa's attempt to do something no country has tried since the 1970s.
From Monday morning, drivers in the Pacific island nation will steer their cars to the left-hand side of roads, instead of the right-hand side they are currently driving on.
The government has pitched the change as economically beneficial, but critics say it will lead to traffic mayhem.
Prime Minister Tuilaepa Sailele Malielegaoi has said the move will allow the tens of thousands of expatriate Samoans living in New Zealand and Australia to send used cars - with steering wheels on the right side of vehicles - to their families back home.
It will also allow used cars to be imported from Japan, which also drives on the left.
Cars will become cheaper, and more people in rural areas will be able to obtain vehicles to help them develop their land, the government reasons.
"The switch in the side of the road for driving is a policy for the development and improvement of life for all the people of Samoa," the prime minister said in August.
There are fewer than 20,000 vehicles on Samoa's roads, and about 4,000 are currently right-hand drive, with half of those recently imported, says Keni Lesa, editor of the Samoa Observer.
The rest are left-hand drive vehicles built to be driven on the right side of the road, imported from the US and neighbouring American Samoa.
The proposed changeover has split opinion in Samoa, with opponents predicting traffic mayhem as confused drivers forget which lane to pull into and pedestrians look the wrong way before crossing roads.
"Cars are going to crash, people are going to die - not to mention the huge expense to our country," says lawyer Tole'afoa Solomona Toa'iloa, who has headed a legal challenge in the Supreme Court against the constitutionality of the plan for protest group People Against Switching Sides (Pass).
Traffic analysts testifying in court agreed that more accidents were likely to occur.
New Zealand crash investigator Graham Williams said there would be more accidents on Samoa's narrow, pot-holed rural roads, which are often obscured by vegetation.
"Based on my experience and from what I've seen during my trips to Samoa, come 7 September, there will be a dramatic increase in the number of road crashes," he told the court.
Local bus owners are also furious about having to either buy new vehicles or convert their old ones - by cutting new doors on the left side behind the driver so passengers don't have to step off into the middle of the road.
One bus company owner has threatened to set his vehicles alight in protest.
In some places, new signs directing drivers to keep left have been removed, and directional arrows on the road have been painted over to point the wrong way.
Complaints have also been raised about the expense. Samoa's Chamber of Commerce estimates that it will cost at least $300m (£185m) in direct and indirect costs to the Samoan economy.
The Chamber of Commerce also questioned the benefits to the agricultural sector, saying that most vehicles in Australia and New Zealand are sedans and wagons and not pick-up trucks or utility vehicles.
Critics also say the government has failed to consult the public on the change or conduct any feasibility studies.
In April last year an estimated 18,000 people - about 10% of Samoa's population - demonstrated against the change in the capital, Apia.
But the opposition has since lost some of its steam, and last week the Supreme Court rejected a legal challenge from Pass.
The president of Pass, Lefau Waikaimoana So'onalolole, said Samoa was not ready and necessary roadwork had not been finished.
"The efforts to prepare for the road switch are nowhere near completed," he said.
"Not only that, but I believe there is much work to be done in educating everybody about the switch."
But Prime Minister Tuilaepa turned down a last-ditch appeal to delay the switch.
"Many preparations have been carried out," he said after a special cabinet meeting held to consider the appeal.
"A repeated request to government from the wider public has been to start the switch on the scheduled date to make it quicker for the country to become familiar to the changes."
He has declared a special two-day holiday on 7 and 8 September to provide time for people to adjust to the change.
"I would envisage at 0550 [on 7 September] we will have a kind of speech through the television, and then exactly at 0600 the call will go, sirens and church bells will ring," he said.