Traffic in Austin is a mess, mainly because the city is long and linear (east-west travel is made difficult by the topography). In increasingly long rush hours, traffic barely moves on either north-south freeway. To solve the problem, the city is adding one lane in each direction to one freeway, but there will be tolls on that lane. Moreover, the tolls will be variable — but not by time of day or day of week. They will vary with traffic speed, rising when the average speed in the lane drops below 50 mph. Pretty neat — peak-load pricing taken to its logical extreme. The technology that makes this possible is fairly recent. And it’s a good example of how technical improvements raise well-being — in this case, allowing those whose value of time is high to substitute money for their time and reducing congestion on the “free” lanes for the rest of us.