Driving around London can be nightmarish at the best of times, but no more so than when you end up sandwiched in an inescapable gridlock. Transport for London's latest tech trial is hoping to make journeys though the capital that bit more pleasant, by using taxi-top signage that tells nearby vehicles where to avoid. Kicking off today, the six-month experiment sees 200 of London's finest black cabs fitted with digital advertising boards that also broadcast live traffic warnings. For now they're able to give you a heads-up on delays in up to London 50 areas, but should the signage be more widely deployed, the idea is to provide richer, real-time updates on congestion as traffic jams are taking shape. Whether we can get our Uber drivers to take the cautionary advice on board? Probably not.