Protestors in Hong Kong have been using traffic cones and leafblowers versus tear gas canisters. As the unrest stretches into month five, they've now come up with a low-cost way to stymie police vehicles: They've been building these little brick "Stonehenges," as observers have called them.
I know what you're thinking: Those are a problem for cops on scooters, sure, but not so much for larger vehicles. In fact the structures are not meant to stop vehicles, but simply to slow them down, particularly the ponderous water cannons the police have been rolling out. So what the police now do is first send out a larger vehicle topple the bricks, and then the water cannons roll in afterwards. And as you can see from the video, it does indeed make the journey slower for the latter type of truck: