How do they do that? Make roads smarter

Photo by Carl Greenlund/Metro

How do they do that? is a series for The Source that explores the technology that helps keep Metro running and passengers and other commuters moving. Some of it applies directly to the trains, buses and freeways and some of it runs in the background — invisible to nearly everyone but essential to mobility in our region.

How do they do that? Make roads smarter

In their future form, smart roads could be the automated highways of tomorrow — the roadways we cruise, possibly in self-driving cars, hooked to a group of other cars headed in the same direction. By traveling together cars can move faster and distances between them can be decreased, since the group accelerates and brakes simultaneously. This maximizes road capacity while it minimizes the chance of accidents, which slow down traffic.

Obviously we’re not there yet. But there are a variety of smart road technologies being used in Los Angeles County and Metro is participating — primarily by helping to fund them — in programs to squeeze more capacity out of streets and freeways. They may not be smart roads of the future, but they are promising advances.

Here’s a quick overview of what’s going on:

•Caltrans and Metro are in talks to mirror a program already running in Orange County on the northbound I-5 freeway. By offering real-time travel comparisons between the freeway and Metrolink, electronic message signs let commuters know when it would be faster to take Metrolink than to stay on the freeway. Comparative travel times would work the same way in L.A. County comparing, say, commute times on the 210 Freeway with the Gold Line speed to Pasadena. The intent is to encourage drivers to consider transit as an option.

•Another kind of sign used to keep traffic moving is the changeable portable sign that is similar to — but smaller than — the permanent message signs we see on freeways. These signs appear at road closures and construction sites, as well as at Staples Center and Dodger games, routing drivers away from congestion.

Transit signal priority is another smart road technique and Metro has been a leader in developing this technology, which is now being used all over the country to speed buses through traffic-clogged city streets. Transit signal priority technology generally results in up to a 20 percent reduction in red light delays for buses.

•Signal synchronization is among the most fundamental smart road technologies. For decades, Metro has been working with cities (there are 88 of them in L.A. County) to enhance the capabilities of signalized intersections. Intersections throughout the county have been coordinated to decrease travel times by 10 to 15 percent on major streets.

In our region, signal synchronization is among the most fundamental of smart road technologies. This is not the same as the loop detectors. More advanced detectors generate speed data that can let the public know which streets or freeways are moving so that real-time decisions can be made about the best route to take to avoid congestion. (The map at is one example.) This information also lets cities evaluate street performance so that adjustments can be made to intersection light timing to help traffic run more smoothly.

•The region also uses several different technologies to enhance communication between signalized intersections and local traffic control centers (TMCs), such as the L.A. County regional TMC in Alhambra. TMCs monitor street traffic and dictate traffic signal changes based on traffic flow. They follow traffic patterns via pavement loops, fiber-optic communications and wireless radio systems. And if the traffic backs up, they make adjustments in real time.

•Another smart road technique can be seen at the northbound 110 and 5 freeway interchange that for years created a log jam at rush hour, as several lanes of cars merged into a single left-hand lane to transition onto the northbound 5. During rush hour, variable lights in the freeway pavement now direct cars into two lanes and this has reduced congestion and improved safety.

•For years we’ve had ramp metering on freeways to release cars one at a time onto the freeway. Adaptive ramp metering — originally tested on the 210 freeway — takes it to another level. It doesn’t just release cars, based on time of day. It actually takes a real-time look at how much traffic is on the freeway so it can better regulate entry. Metro is currently working with Caltrans to determine if the 210 freeway metering test should be expanded.

•Also coming up is ExpressLanes — the high-occupancy toll lane strategy to better manage demands on our freeways and streets. Metro, in partnership with Caltrans, sought and secured a federal grant to develop and implement it. The one-year demonstration begins on the I-110 Harbor Freeway in October and on the I-10 in early 2013.

•Another smart road initiative coming up soon is aimed at collecting data to improve bicycle safety. There have been a number of changes in state law that mandate bike detection for safety so that signalized intersections can tell the difference between a bike and a car. Metro and its local agency partners are investigating the use of several different technologies, including cameras and wireless magnetometers and other sensors embedded in roadways. One promising technology that Metro and the city of Santa Monica are beta testing is a micro-radar device that sends out a radar signal that can, based on size, differentiate between a bicycle, a car and even a pedestrian.

Eventually we’ll have autonomous vehicles that can talk to one another. But not yet. In the meantime, these small smart road changes add up to minutes saved and the technology will be part of a larger plan that not only will save us time, but make our travel safer. And that, of course, is the most important thing.

4 replies

  1. Saw a CHiP today tag a cabbie for making the 110N to 5N from the #2 lane when the sign was not on for it.
    Schadenfreude at its best.

  2. “For years we’ve had ramp metering on freeways to release cars one at a time onto the freeway. Adaptive ramp metering — originally tested on the 210 freeway” — I SEE, so that is why the ramp meter signals from the NB 605 to the EB 210 (in Irwindale) are turned off, that was a test? They have been off for a while now. When they are off, traffic on the EB 210 is backed up all the way to Pasadena sometimes. I have written to CalTrans, but no response yet, METRO, please look into it or hurry up with the Gold Line Azusa extension, thanks.

  3. “Another smart road technique can be seen at the northbound 110 and 5 freeway interchange…. During rush hour, variable lights in the freeway pavement now direct cars into two lanes and this has reduced congestion and improved safety.”

    Many drivers ignore the overhead signs and use the second lane at any time. Most drivers pay attention to the signs and follow rules, but there are some that don’t. I would suggest that the signage be changed to a lit changable sign. “I-5 Left Lane ONLY” and then ” I-5 ▼ ONLY I-5 ▼ OK”. Also increase the LED’s on the pavement at the end and have them amber across the opening from the #2 lane (or even further back. )