"Shared vehicle, doesn't park, doesn't occupy curb space"

"Shared vehicle, doesn't park, doesn't occupy curb space"

This was the claim I heard made about shared vehicles. First off, the vehicle is rarely 'shared'. If the driver is in the vehicle, that's not a 'shared' ride. You are being chauffeured. The driver is not a passenger. (If I drive my kid to school, it's not a 'shared ride'--I'm driving him to a place, being a 'taxi-mama'.) It's only a shared ride when there are 2+ passengers in the car. Which is rare. How rare? In my experience, perhaps 1% of all the rides I've ever taken, did I share a ride with someone. (And that was in a major metropolitan city).

"Shared vehicle, doesn't park, doesn't occupy curb space"
A TNC is just a dial-a-ride taxi with a better fare structure. Taxis occupy curb space. They aren't in motion all the time. (Or perhaps even most of the time). They _do_ require parking space. That said, taxis are probably in motion more than TNCs, because they spend much of their time 'cruising' for fares, rather than parked and waiting for fares. So Taxi's probably take up more road space  than a TNC would (a moving car taking up about 3x as much space as a parked car, due to safety-required separation between two moving cars.)

I have seen Lyft Vehicles, pulled over on the side of the road, checking their phones, as they wait for Google maps to locate their next fare in the queue. (Peak times, not so much, as trips get added to the queue faster). 

Do they take up space in the middle of the day? Ie, do they take up all-day parking space, the way that a car driven to work does? No, clearly not. But cars still need to be stored someplace. (Likely in whatever suburban wonderland TNC drivers live). Which brings up a VMT issue: If a TNC driver drives someone to work, then drives home. Then, in the afternoon, drives someone from work to the grocery store, and then someone else from the store to home. Then they drive themselves home. Point being that the driver made two trips home (one morning, one evening) to drive one person to and from work. So if we assume that everyone will take a TNC to work, VMT is going to explode. Rule of thumb (from a PhD student who drove UBER was he drove 1.69 miles for every passenger mile). So 69% more VMT, to achieve the same amount of mobility? The roadway network will never withstand that kind of increase.

 Of course, it might. If the demands on the roadway network were spread over a wider period of time. Presumably, fewer drivers want to drive during congested conditions, because it's slower. And while they get paid both per mile and per minute, I believe the incentive structure also pays them by trip. So there is a strong incentive to maximize the number of trips you make. And even if not, it's better to be earning for both miles and minutes than sitting in traffic. 

So you have fewer drivers during congested times, and people have to wait longer to take a TNC during congested times. (So the reliability declines, and more drivers are inclined to say "Screw it, I'll just drive myself"). At which point, you've basically enacted congestion pricing. Ie, when things are congested, it costs more to drive.