Bollards can put an end to car-park disputes. He and several other installers say they are doing a roaring trade as parking skirmishes grow. One company says it has installed about 450 bollards nationally in the last six months alone. Parking woes are making people angry. Very, very angry. "One guy had a car spot in St Kilda, and this other guy kept parking in this spot," Mr Strachan said. "So he put a bollard in – and the other guy ripped it out. So then we core-drilled the concrete, poured a slab, really put it in. Then he dumped all his hard rubbish out into the car spot. That's how extreme some of these people get."

Suzy and Joe Luppino of SecureSpot Credit:Simon Schluter When Joe Luppino​ worked as a building manager at a Southbank high-rise he would get calls "all the time" from someone furious about having their private car-parking space nicked. "Legally within buildings you can't have the car towed away, and the police can't do anything about it," says his wife and business partner Suzy. "They're just frustrated, they're pissed off. They're sick of it. Sometimes it's the same person over and over again parking in their spot, when they're at work. "There's nothing you can do – except get a bollard."

A City of Melbourne spokeswoman said parking inspectors were unable to ticket people parking in other peoples' private car-spaces as they were private property. Suzy and Joe set up SecureSpot to sell $350 remote-controlled bollards six years ago. After a slow start, they say business is now booming. The Luppinos say business growth is being driven by the increasing number of people living in high-rises and parking in private car-parks. They and other companies say they do most of their trade in the CBD and inner suburbs. "As more places are going up, there's going to be more people, more cars, and more unauthorised parking – which is great for business," Ms Luppino says. But many people are also installing private bollards on residential streets – especially near shopping centres and train stations, where parking often overflows.

Stuart Bell, general manager at Barrier Group, estimates he sold about 450 private bollards in the last six months. "There are people who back onto lanes and have parking out the back, people who live behind shopping centres. It's a fairly widespread problem – I'm amazed we only sell 450," he said. A City of Melbourne spokeswoman said no planning permit would be necessary to install a bollard in a private car parking space – although owners corporation regulations might apply. Customers wishing to install parking bollards on external car parking spaces would need to apply for a planning permit depending on the location and specific planning controls that apply, she said.