The utility of an Uber Pool or Lyft Line ride is hard to deny. Those services match drivers to riders heading in the same direction. Doing so, they allow drivers to reduce total costs and translate those costs into cheaper fares. Efficiency! Sharing a ride thus means saving a good amount of money. A standard Lyft trip that might cost $14 can be as little as $3.50 in a Lyft Line. The savings quickly add up.

Such rides carry a conundrum, however. Namely, what is the etiquette of sharing a ride with another passenger?

This matters, because users of Pool and Line are likely to increase in the months ahead. It's a good service.

Yes, you have to share with a stranger, but you still get picked up, you still get a seat, and you still get dropped off. In most cases, the added journey time is small.

Of course, occasionally, you have to travel with a moron who is too rude to enter the car quickly, or too stupid to know where they're heading.

But then comes the etiquette question.

Should you talk to the other passenger?

I say, yes. At the beginning at least. A simple greeting does not require effort or a necessary response, but it establishes a baseline of respect for the rest of the ride. It also serves another purpose. It offers an introduction to a possible conversation. I've had numerous rides where a simple greeting has led to a chat on tipping, or politics, or my accent (it's British).

But sometimes we don't want to talk. In that case, returning a greeting and then looking down at one's phone is a good way to send the signal of disinterest. The phone maneuveur is useful because it employs a presumption of deniability. Looking down at your phone, you send the message: "Hey, I'm not being rude, I'm just working on my phone."

Yet it's also useful for a second reason. It helps a driver sense whether passengers are open to talking. If they are, the driver will normally act as a conversation facilitator. But if one phone comes out after an attempt at conversation between two passengers, the driver knows to talk to the first passenger so that the second cannot. Drivers are very good at this. After all, with hundreds or thousands of rides under their belt, they know how to read people.

Anyway, that's a primer on politely ride sharing with other passengers!