FIELD GUIDE · Tracking & Intel
How Live Traffic Maps Work: Reading Road Speeds in Real Time
Where does live traffic data actually come from?
The colored roads on a live traffic map feel almost magical — somehow the map knows that the interstate is jammed and the side street is clear. The secret isn't a network of cameras watching every road. It's something subtler and far more powerful: the roads are being measured by the very vehicles driving on them.
Where the data comes from
Live traffic runs mostly on floating car data — anonymized GPS signals from millions of smartphones, navigation apps and connected vehicles. Each one is a moving probe. By watching how fast those probes travel along a given stretch of road, and comparing it to that road's normal free-flow speed, a provider can tell in near real time whether traffic is cruising or crawling. No single driver is identifiable; it's the aggregate motion that matters.
On top of that speed picture sits incident data: crashes, road closures, construction, stalled vehicles and major jams, gathered from traffic-management centers, emergency feeds and crowd reports. LEV draws both — a flow layer showing how fast the roads are moving, and an incident layer marking what's blocking them.
Reading the colors
Traffic flow is shown as color relative to normal speed:
- Green — moving freely, at or near the road's usual speed.
- Yellow / orange — slowing; building congestion.
- Red / dark red — heavy congestion or near standstill.
The key word is relative. A road can glow red at 30 mph if it normally runs at 65 — the color is about delay, not raw speed. That's what makes it useful: it flags where you'll lose time compared to a clear run.
Why it only covers roads
Traffic data exists only where there are roads and enough moving probes to measure them. Empty countryside, oceans and quiet lanes have nothing to report, so the layer naturally concentrates on cities and major corridors. Zoom into a metro area and the whole network lights up; zoom out and you'll see the big arteries. This is a layer that rewards zooming in.
Reading it with the weather
Weather and traffic are deeply linked — bad weather is one of the largest causes of congestion and crashes. That makes the pairing especially revealing:
- Add Precipitation Radar. Watch a band of heavy rain cross a city and, minutes later, the roads beneath it redden and incident icons pop up.
- Use the Storm Commute fusion. We bundle radar + traffic into one tap, so you can see weather hitting the roads in real time.
- Stack it with Power Outages. A severe storm can knock out signals and power and jam the roads at once — three layers telling one story.
Used together, the traffic and weather layers turn an abstract forecast into something concrete and personal: not just "rain this afternoon," but "the rain is here and the commute home is already turning red."
Frequently asked questions
Where does live traffic data come from — is it cameras?
Almost never cameras. Modern traffic data comes mostly from 'floating car data' — anonymized GPS signals from millions of smartphones, navigation apps, and connected vehicles moving along the roads. By measuring how fast those probes are actually traveling on each road segment and comparing it to the road's normal free-flow speed, providers build a live speed map. Incident data (crashes, closures, roadworks) is layered on from traffic authorities, emergency feeds, and user reports.
What do the red, yellow and green roads mean?
They show speed relative to normal. Green means traffic is moving at or near the road's free-flow speed. Yellow and orange mean it's slowing down. Red — and dark red — mean heavy congestion or a near standstill. Because it's relative, a road can show red even at 30 mph if that road normally runs at 65, so the color is about delay, not absolute speed.
Why does LEV's traffic layer cover roads, not the whole map?
Traffic data only exists where there are roads and enough moving probes to measure them. Open country, oceans and lightly traveled areas simply have no flow to show. Zoom into a city and the road network lights up; zoom out to the globe and you'll mostly see major corridors. The layer is at its best at metro and regional zoom.
How do traffic and weather connect on the map?
Tightly — weather is one of the biggest causes of congestion. Rain, snow, fog and flooding slow everyone down and trigger crashes, so a band of heavy rain on the radar is often followed by a bloom of red roads and incident icons beneath it. Turn on Traffic with Precipitation Radar (we bundle this as the 'Storm Commute' fusion) to watch weather snarl the roads in real time.
SEE IT LIVE
Everything in this guide is on one real-time map.