This is part two of a series on changes that driverless cars may bring. I expose some of the ideas I have, mostly quite practical things. We moved project troglodyte to it’s own website, so the more patent centric recap of the Google driverless car patents can be found from there.
Below I assume that the problem has been solved completely. Driverless cars can access any part of the road network, function even when there are people darting around and can handle any weather including lots of snow and very slippery conditions. Accident levels are same or lower than currently and people are not scared to use autonomous cars.
Just like the difference between rental cars and taxis will dissolve, mass transportation will also overlap more with taxis. This is because currently cost of drivers pushes public transportation towards larger vehicles and less frequent service. The larger the vehicle is, the smaller the change in cost structure as personnel costs become less important in trams and trains due to their larger passenger capacity. Smaller busses and more frequent operation will become a practical proposition.
While taxi traffic probably also scales nonlinearly this is certainly true for public transportation. More people travelling leads to more frequent operation, it will be easier to change between lines, journey times will be shorter and prices will be lower. This would seem to indicate that busses would benefit greatly from being able to operate autonomously. The optimum transition point between operating a bus or a tram/light rail would also likely be different. With current arrangements it is difficult to operate busses with very short intervals, as this leads to busses travelling right behind each other with some full and others empty. With smaller busses it would be possible to operate slightly different parallel routes if the geography of the area allows it. In many cases this is not possible and it would still be necessary to use a higher capacity transport mode.
Currently there seems to be a psychological limit for the minimum size of public transport, people don’t want to get into a small vehicle with strangers. There are some fully automated rail systems in operation and in many trains the operator is not able to intervene to assist if there is some trouble, so this doesn’t seem to be a big problem for large vehicles, but it can be a limiting factor for smaller ones.
Passenger density is larger for big vehicles and the possibility of some passengers standing during rush hour gives some flexibility in exchange to some discomfort. A large vehicle can also have large doors enabling fast boarding, this is an important factor for high throughput mass transportation with many stops. For very small vehicles the same road or rail network would still be able to handle less passengers despite the smaller headway enabled by the automation of the vehicles.
Vehicle costs also differ between small and large vehicles, small ones can be mass produced with fairly low cost, while larger ones likely have lower maintenance costs per capacity. Small vehicles can idle when not needed, but large ones need to run half empty during off peak hours. Most likely different solutions will be used in different environments to optimized between the comfort of small, even one person vehicles and the higher capacity of larger ones.
Acknowledgment: Thanks to Laston Kirkland for thoughtful evaluation of these ideas.