This is a very interesting report. It was based on anonymized tracking of cars with cell phone GPS signals to better understand the whole traffic network of the Bay Area. Identifying choke points for traffic led to a policy proposal.<p>"John Goodwin, a spokesman for the Metropolitan Transportation Commission, the region's transportation planning agency, says the best way to spread out traffic coming from these neighborhoods is to install metering lights at their freeway onramps, which spaces out the traffic to help both those drivers and everyone else get to their destinations quicker. Though many important Bay Area freeways already have metering lights, such as Interstate 280 in the South Bay and Interstate 680 in the East Bay, others don't."<p>The Twin Cities metropolitan area, where I live, was the first place in the United States to gain special federal permission to put on-ramp metered signal lights on federal Interstate Highways used heavily by commuters. They empirically help a lot in smoothing traffic. One reason we know that is that for a while a doofus state legislator shut down the freeway metered ramp program, until traffic here became so unbearable that the meters were put back in use. I have heard from friends who travel here from other parts of the country that the ramp meters (implemented as red-yellow-green traffic signals just before a car gets onto the freeway) are confusing to people who usually drive where on-ramps are just unimpeded paths onto the freeway. But they definitely speed up traffic.<p>The Twin Cities has one federal highway, Interstate 394, with a pair of reversible lanes, usually eastbound (into Minneapolis from the suburbs where I live) in the morning, and westbound (out of the city into the suburbs) in the evenings. That helps with rush hour commuter traffic, except that a lot of cars are eastbound for evening appointments even as commuters are leaving the city, so the reversal of lanes still leaves the regular, nonreversible lanes badly congested each evening. I wonder if a traffic study like the one reported in the interesting article submitted here could identify how to smooth out the traffic problems we still have here.