The concept of shared ride services — if I’m heading into town, you can ride with me and we’ll split the cost — is so intuitive that both Lyft and Uber are launching it at the same time. Car pooling has been dropping steadily since a high in the '60s and early '70s, but cellphones are helping to revive it.

At Lyft it’s called Lyft Line. At Uber, UberPool. Both are in local testing mode in the San Francisco area, but plan a rapid expansion.

Uber X driver

Photo: Uber

The two companies, which have clearly struck a nerve in their bids to overturn the taxi business as we know it, are tapping into the growing power of the mobile phone to dominate nearly every aspect of our lives.

At Lyft, Line is simple and designed to save you up to 60 percent off a regular ride from the service. It works like this: You open the app on your phone and select “line,” then “request line.” You’re prompted to enter a destination, and then Lyft comes back with an offer of a fixed-price ride. A text tells you when the car is outside. “Even if we don’t find another passenger, your Line will remain the discounted rate,” Lyft says.

UberPool is similar. Ask for a ride along a specific route, and within a few minutes Uber comes back with a match, and notifies you with a message something like, “You’ll be sharing your ride with Michael. Your driver will pick you up first.” And like Lyft, you get the discount even if the company doesn’t find someone to share your ride.

UberPool, the company says, works toward its goal of “making transportation so inexpensive and reliable, people can actually sell their cars.” Uber wants to have “tremendous and inspiring impacts on congestion and pollution,” and it probably will—if it can make it through the regulatory thicket and the hostility of the taxi industry.

I expect these services to work out fairly well. After all, as the New York Times points out, more than 100 million Americans drive to work alone every weekday. “The [Lyft] plan is a clever way for a car-sharing app to go beyond reducing our dependence on private car ownership,” wrote the Times’ Farhad Manjoo. “With car-pooling, it could end up reducing the number of cars on the road.”

For consumers, this is a pretty good option. The dangers are fairly obvious — that the driver who picks you up is a nut job, or a wild driver. But variations on this have worked out well so far. Companies like Enterprise Rent-A-Car offer vanpooling services, with each full van taking nine cars off the road. In some parts of California and elsewhere, there are “casual car pools” — known places where ride seekers can wait and get picked up. Click here for some locations around San Francisco and the East Bay.

California became the first state to legalize private ridesharing with a 5-0 vote of the Public Utilities Commission last year. Technically, it enables “transportation network companies.” Sidecar was just one of the outfits that had already started offering these kinds of cell-enabled rides in 2012. But Sidecar, Lyft, Uber and Tickengo were all issued cease-and-desist orders that year, instructing them to wait until the regulations were in place.

Unless some horrendous accident occurs, we should all be able to try out this form of ridesharing. Insurance is key here, and that’s why it was fortunate that RelayRides had a $1 million policy in place when a client borrowing a Bostonian’s car got into a fatal accident. The four people injured in that collision sued, and the case was settled out of court, presumably at no cost to the car’s owner.

Related on MNN:

Jim Motavalli ( @jmotavalli ) writes about cars, technology and the environmental world to anyone curious enough to ask.

How to use your phone to share a ride
Uber and Lyft are both offering discounted ridesharing services. Today in San Francisco; tomorrow the world.