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 does Go511, the automated phone and web service, know when freeways are jammed? How does it know what we're saying when we ply it with questions about traffic? Can it tell from our voices when we're starting to panic?

Go511 is the five-county, toll-free phone and web service that provides verbal and digital 24/7 updates on traffic and public transit. It's updated constantly so the answers are there when we need them and they change every minute with the flow of traffic.

If you're driving to the airport and running late for your plane you can call 511 on your hands-free phone and the service will verbally deliver estimated travel times including accidents, bottlenecks or potentially dangerous road conditions between you and the airport.

If you're standing on the street waiting for a bus, you can connect to real-time Metro bus arrival info on your phone by dialing 511. Go 511 also has info on ExpressLanes, L.A.County's brand new high-occupancy toll lanes. Go 511 also can provide trip planning for public transit, carpool and vanpool options through links to Metro’s trip planning tool on the metro.net home page.

But how does it do all that?

Real-time traffic on Go511 comes from wired loops embedded into our freeways. As vehicles pass from one loop to the next, the data is collected and sent to a Caltrans computer that calculates vehicle speeds. These are delivered to the 511 database so that when we ask a question, the database can convey the answer to a computer that translates it into human language.

Planned road and freeway closures for maintenance and construction are sent by Caltrans to Go511. Accidents, incidents and road conditions that affect freeways, such as Sigalerts, icy roads or flooding, are delivered by the California Highway Patrol as soon as they are reported. Metro real-time bus arrival information comes from Nextrip and bus schedules are available for all transit providers in Southern California, including Metro and Metro Rail. Web accessible Trip Planner links are also available for all of Southern California on the website and for Los Angeles and Orange Counties by dialing 511.

Speech recognition software — which translates spoken words into text — allows the 511 computer to understand what we are saying through complex coding algorithms that have to recognize not just words and word patterns but differing accents and tones of voice. We would not understand the computer response on its own. So a human voice is recorded and matched to the computer signals that are matched to words and thoughts that are appropriate responses to likely questions.

The recorded voice of 511 is a woman named Camille who says things like, “What can I help with? Traffic, public transit, commuter services or motorist aid?” If we say “traffic,” Camille's voice asks us, “Which freeway or traffic hotspot do you want to hear about?” If we say, “405 between 170 and 10” it repeats what we have said and asks “OK?” It then answers the question.

To help the computer speak in this manner, Camille has recorded thousands of words and phrases including every street name in Los Angeles and Orange counties, the names of freeways and landmarks such as “Union Station,” “StaplesCenter” and “Disneyland.”

It has also been programmed to recognize aliases, including LACMTA, LAMTA and MTA for Metro, MLK for Martin Luther King Jr. Boulevard, as well as San Bernardino Freeway, Santa Monica Freeway and the 10 for Interstate 10. If it doesn't understand a request it generally offers options that are similar.

But how does the system piece together the correct answers? The database contains thousands of answer options and it matches those with the constantly changing real-time conditions provided by Caltrans, CHP and others.

And no, 511 doesn't have any idea when we're in panic mode, although the assumption of the developers could well be that most L.A. motorists are in panic mode, most of the time.