To every age dogged with pollution, accidents and congestion, the transport solution for the next generation seems obvious – but the same problems keep coming back

In the 1890s, the biggest cities of the western world faced a mounting problem. Horse-drawn vehicles had been in use for thousands of years, and it was hard to imagine life without them. But as the number of such vehicles increased during the 19th century, the drawbacks of using horses in densely populated cities were becoming ever more apparent.

In particular, the accumulation of horse manure on the streets, and the associated stench, were impossible to miss. By the 1890s, about 300,000 horses were working on the streets of London, and more than 150,000 in New York City. Each of these horses produced an average of 10kg of manure a day, plus about a litre of urine. Collecting and removing thousands of tonnes of waste from stables and streets proved increasingly difficult.