Concrete balls: Indonesia takes extreme measures to stop fare-dodgers
The Indonesian rail network has been struggling for years with increasing passenger numbers. Commuters often ride on the roof simply to avoid the overcrowded carriages, although it is also a popular tactic for avoiding paying fares. Many also "roof surf" simply for the thrill of it.
The authorities have already installed several dozen balls at stations around Jakarta. If they prove effective, the project will be expanded across the country.
The balls are the latest of a string of deterrents for roof surfers. In the past, authorities have tried spraying them with red paint, threatening them with dogs and putting barbed wire on the roofs - all to no avail.
While the tactic has caused alarm among some passengers, many are planning to carry on regardless.
Speaking in the Sydney Morning Herald, one passenger said he would not be deterred.
Muyanto, 27, a shopkeeper who travels from Bogor to Jakarta every day, told the paper:
"I was really scared when I first heard about these balls. But I don't think It'll last long. They've tried everything - in the end we always win. We like it up there. It's windy, really nice."
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