Part of the reason why the roads are so congested is that the standard working week we've inherited dictates that the working day should run from Monday to Friday between nine to five.
Barnes says that the key insight underpinning his experiment is that flexible working hours don't hinder productivity and that staff should be given greater freedom to select the times they feel are best suited to achieve their employment objectives.
If businesses are able to offer some staff members the opportunity to work to different schedules, then this would, in turn, have the knock-on effect of fewer vehicles on the road.
"If you're allowing them to work flexi-hours spread over five days, you're spreading the traffic and that has implications for infrastructure."
While the four-day week has been envisaged as working from Monday to Thursday, Barnes argues that this should also be up for debate. Some people might prefer to work on Saturday and Sunday, he argues they should be allowed to do that as long as they can still deliver what's required of them.
"Productivity should be the basis of discussion, not working hours," Barnes told the Herald.
As much as the four-day week has been a social experiment, he says it's also a conversation starter.
"These are interesting issues, and we should be debating them because I think it changes the composition of society," Barnes says.
"And once that changes, the opportunities available for people will change ... I don't know what the outcomes will be, but I would say to all business owners, be a little creative, think about trying a few things."