Indonesia has long fought a losing battle against commuters who stubbornly ride on train roofs to beat the rush hour . But railway officials say they have found the perfect deterrent , concrete balls , suspended on chains from a steel frame , just 25 cm or 10 inches , above any passing train . Dubbed `` Goal Balls '' , they are about 10 cm or 4 inches in diameter and are painted silver . Twenty four , a dozen on each side , are suspended from a frame that looks like a soccer goal . The first one was installed early this week , a few hundred yards from a train station , just outside Jakarta . Anyone riding on the roof will find it hard to dodge the balls . Mateta Rizahulhaq , a spokesman for the state-owned railway company PT Kereta Api , told CNN no one has dared an attempt it . `` From our field reports so far , there have been no roof riders on that line since we installed them , '' Rizahulhaq said . Over the years , officials have tried and failed to stop commuters from climbing atop carriages . `` Policing passengers has been going on in various ways for so long . Starting with oil on the roof , using barbed wire , spraying dyed water , dogs , advice from religious leaders . None of these were effective , '' explained Rizahulhaq . Some critics say this latest tactic seemed too extreme . `` It 's not that we do not have humanity , but from the time someone gets up on the top of the train , they just do not value their life anymore , '' Rizahulhaq added . Almost half a million commuters depend on the railway system to travel within the greater Jakarta area . Trains are packed , especially during the rush hours . Many passengers choose to climb to the top of overcrowded carriages . There are some -- train surfers -- who get on for a free ride or just for the thrill of it . Officials say these thrill rides cause one or two deaths per month . They hope the new measure will prevent any more fatal accidents . If the concrete balls prove to be effective , more will be installed in other areas of the capital , officials said . The government predicts that by 2018 , the number of train passengers in Jakarta will increase to over a million . Everyone here agrees that what this growing metropolis needs is an improved and expanded railway system that gives passengers no excuse to get on train rooftops .
The concrete balls are suspended just above the passing trains . The railway has fought a losing battle to keep riders off the top of trains . Almost half a million commuters depend on the rail system in greater numbers .