Is it legal to carpool?

Dynamic car pooling: a fraction of the cars would be enough

The idea is simple, and the potential for savings is obvious: Instead of booking your own taxi for the entire journey, you jump on board with one that is going to the desired area anyway. On the way, the driver collects more passengers and drives them all to their respective destinations. The multiple occupancy reduces the number of journeys - and thus the number of cars that turn through the city in search of passengers.

Smartphones and satellite navigation make this possible. Anyone who is logged into the system forwards their location and destination via the app; Drivers with space for passengers get the route to the next passenger fed directly into their navigation system. A central computer brings both parties together. The more participants take part, however, the more demanding the calculation becomes, especially when each car has space for half a dozen passengers.

Now, however, scientists working with Daniela Rus from the Massachusetts Institute of Technology have developed an algorithm that does not fail even if it has to take into account thousands of interested parties at the same time. This makes it possible to handle Manhattan's entire taxi traffic in real time.

According to the simulation, this could significantly reduce the vehicle fleet, the researchers say in their study: Under the most favorable conditions, 2000 large taxis with space for ten passengers are sufficient. If you use normal cars with space for four passengers instead, the number rises to 3,000. There are currently almost 15,000 active taxis in downtown New York. In all cases, the system can be fine-tuned so that the average waiting time is less than three and the additional journey time is three and a half minutes - which is roughly the time it takes to get your car from the parking lot, throw in Rus and colleagues . According to the simulation, only around two percent of all travel requests cannot be covered with a practicable ride-sharing option.

For taxis, private individuals and autonomous cars

For these tests, they used the passenger volume of a typical New York week. They obtained key data from a public database for all three million taxi rides that took place in Manhattan between May 5th and May 11th, 2013. Then they let the computer form the most efficient car pools.

According to the same principle, not only taxis but also private trips can be merged - or in the future also the trips of autonomous vehicles. These could circle through the city centers all day and pick up passengers again and again. A special function of the algorithm also allows unused vehicles to be sent prophylactically to areas where a high demand is expected. Fewer cars on the roads would reduce both air and noise pollution, but would of course also have the advantage of producing fewer traffic jams.