Japanese cars are not otherwise distinguishable by their frequent mid-block stop-and-wait actions, for instance, nor for diverting commuters from public transportation.
Read the actual paper. They seem to have used two methods to make the alternative ("counterfactual") scenario more realistic than just "remove Uber cars":
- They compare increase in congestion and Uber/Lyft activity for short road segments, and show that these two changes correlate
- They compare reality to a model that does not include ride sharing, but does model increased population etc. This (generally well-regarded model) shows lower increases in congestion in a world without ride sharing.
Increases in congestion at popular drop off / pick up sites are not necessarily bad. It could be that dropping people off is the new bottleneck because the rest of the road network is less congested, and now there are more trips (i.e., the road is providing more value because it is more efficient).
A study that measured door-to-door time, and the number of passenger-miles per hour would be much more useful.
I’m not sure why traffic engineers refuse to use metrics that are directly related to the quality of the experience for the people using the roads, or the economic value delivered.
That's fair, but a certain percentage of Uber and Lyft customers are people who would otherwise drive their own car, so any study that removes the effects of Uber- and Lyft-operated vehicles altogether paints an inaccurate picture.
The point is not (so much) the number of cars, the point is the different behaviour. Self-drivers will go as smoothly as they can from one parking location to another. Uber and Lyft drivers will loop until they get a ride and stop disruptively at the beginning and end of each ride.
Their behavior is better than people circling endlessly looking for parking. If traffic is worse, but more people are getting the places they want to go faster, isn't that an improvement in the transportation system?
Stop disruptively? What does that even mean. Do taxis also stop disruptively according to your definition?
> Uber and Lyft drivers will loop until they get a ride
I ride Uber almost every weekday twice a day. I'd say about 80% of the time the driver has their next trip queued up before my trip ends.
What Uber has done for cities is reduce the number of people who drive in to work and then spend 15 minutes looping around looking for a place to park, possibly multiple times each day.
The problem is that in SF those people were already using taxis in a lot of cases but people were limited by price. By making taking a taxi cheaper, you are practically guaranteed to increase the number of cars in flight at any one time.
I don't understand why they don't just replace the Uber vehicle with a "normal" driver then draw conclusions from that. How much worse do they make traffic compared to a "replacement driver"?
Japanese cars are not otherwise distinguishable by their frequent mid-block stop-and-wait actions, for instance, nor for diverting commuters from public transportation.