Trazo rates the streets and paths it routes on from 1 (low stress) to 4 (very high stress), so it can steer your bike route away from traffic.
The ratings are guidance, not a guarantee. Verify safety yourself.
Level of Traffic Stress (LTS) is a 1-to-4 scale from bike planning that rates how stressful a street feels on a bike. It comes from a 2012 report for the Mineta Transportation Institute.
Trazo's levels are our own estimate, inspired by LTS. They aren't an official LTS rating: a full LTS study looks at more than we can, including the details of each intersection.
Trazo reads what OpenStreetMap says about each street: the kind of road, and whether it has a bike lane or a path. For a street with a painted lane, the speed limit and the number of lanes count too. We don't have traffic counts.
Here's how Trazo rates common streets and paths.
The most comfortable choice, with little or no traffic beside you.
A comfortable choice for most riders, with some traffic or a rougher surface.
A choice to ride with traffic and accept the risk that comes with it.
A choice to ride with main-road traffic and accept the risk that comes with it.
The biggest roads, service roads and most sidewalks aren't in Trazo's network, so they have no rating and Trazo doesn't route on them.
No. On a neighborhood street, a painted lane rates level 1. On a road with a speed limit of 35 mph or more, or with 4 or more lanes, the same lane rates at least level 3. The paint doesn't change how fast the cars next to you are going.
If OpenStreetMap has no speed limit or lane count for a road, its road type decides the level. So a fast road with missing data can read lower than it should.
A busy road is a street rated level 3 or 4 with no bike lane.
"Off busy roads" is the percent of a ride's distance that isn't on a busy road.
A painted lane on a level 3 or 4 road doesn't count as a busy road here, because you aren't in the car lane. It can still feel stressful, so the ride page says where it is, and the percent stops at 99%.
So 100% means no busy road and no painted lane on a level 3 or 4 road, not even a short stretch.
"On trails and paths" is the share of the ride that's away from the road altogether.
Only a little. Crossing a level 3 or 4 road where nothing stops the cars adds a small fixed cost, the same in every rider profile. In the With kids profile, that's about what 260 feet of trail costs, so a route won't go far out of its way to avoid one.
Trazo marks the ones left on your route, on the map and on the route card, but it can miss some.
Here a painted lane makes no difference. A level 3 or 4 road counts as busy with or without one, because paint doesn't help you get across.
A crossing gets marked when there's no traffic light or all-way stop within about 65 feet, in any of these cases:
A plain stop sign usually stops the side street or the trail, not the busy road, so it doesn't clear a crossing. The one exception is a bike-lane street that ends at the road at a stop sign. A signal mapped as a fire-station signal or a blinking light doesn't count as a light.
A marked crossing is a cost, not a ban, so a route can still use one. Check those spots before you go.
In the app you pick a rider profile: With kids, Relaxed (the default) or Anything. Each profile gives every kind of street its own stress multiplier.
Each stretch of a route costs its length × its stress multiplier. Trazo adds those up and adds a small cost for each marked crossing. Surface settings, private roads, going the wrong way on a one-way street and the Prefer flat option can raise the cost too.
The lowest total wins, then the With kids and Paved rules below can change the pick. So Trazo doesn't always take the shortest way.
These are the starting multipliers for paved streets and paths in each rider profile:
| Street type | With kids | Relaxed | Anything |
|---|---|---|---|
| Trail or bike path | ×1 | ×0.85 | ×1 |
| Neighborhood street with a bike lane | ×2 | ×1 | ×1 |
| Neighborhood street | ×7.5 | ×1.25 | ×1.25 |
| Painted lane on a main or fast road | ×15 | ×12 | ×3 |
| Through street, no bike lane | ×42 | ×12 | ×3 |
| Main road, no bike lane | ×126 | ×36 | ×9 |
So with the With kids profile, one mile of through street with no bike lane adds the same route cost as 42 miles of trail. That's why a route will often go a bit farther to avoid it.
Favors trails and paths, and uses quiet streets to link them.
Quiet streets and bike lanes on slower roads are fine, leaning a little toward trails.
The most direct route. Busy streets still count extra, so it isn't always the shortest line.
The With kids profile leans away from traffic. You know your kids best, so check the crossings and the road before you go.
If the low-stress way on an A-to-B ride is more than 1.6 times the direct way, Trazo looks for a shorter one. That shorter way can add no more than about 330 feet of busy road or painted lane on a main or fast road, and no extra busy crossings.
If there isn't one, Trazo keeps the long way only if it really rides less busy road than the direct way, and the card says how much busy road is on the direct way.
Sometimes every route Trazo finds has busy stretches. Then the card says so: "No calm way here: every route rides busy roads."
A ride makes our rides-with-kids guides only if it has no busy crossing warnings and rides no more than about 500 feet on a busy street or in a painted lane beside fast traffic. Each of those stretches is named, so you can plan for it.
Trazo sorts every surface into three groups:
Paved strongly prefers pavement, but low stress comes first, so a route can still use gravel or dirt.
Trazo keeps the paved-first route only if it adds no more than about 330 feet of busy road and is at most 1.25 times as long as the Mixed route. Otherwise you get the Mixed route.
When a Paved route has more than a little gravel or dirt, the card says "No fully paved way" and how much. A fully paved way may still exist, even when Trazo chooses gravel or dirt.
Mixed (the default with With kids and Relaxed) prefers pavement, will take firm gravel, and avoids dirt without ruling it out. Any (the default with Anything) counts every surface the same.
If the map doesn't give a surface, Trazo assumes streets, bike paths and sidewalks are paved, and a plain path usually counts as rough unless it's marked for bikes.
Here are two Fort Collins routes on the Relaxed rider profile, and how to read the numbers.
CSU (the Oval) to Spring Canyon Park: 5.1 miles, 100% off busy roads, 63% on trails and paths.
The ride stays off busy roads. But at mile 4.1 it crosses South Taft Hill Road with no traffic light. The percent counts where you ride, not where you cross, so read the crossing list too.
Old Town Square to Lee Martinez Park: 1 mile, 83% off busy roads, 50% on trails and paths.
This one rides busy blocks: East Mountain Avenue, West Mountain Avenue and North Mason Street. At mile 0.5 it also crosses Mason Street with no light. On a ride this short, a few blocks move the percent a lot, and the ride page names them.
We rebuild each area's map from OpenStreetMap from time to time, so a change on the ground can take time to show up.
So look the route over before you ride, and ride to what you see.
Tap Feedback in the app, or email [email protected]. We read every report. Some fixes go on our own short list of local corrections, others change the routing rules, and some take time. Fixes you'd notice go on What's new.
Last updated November 6, 2026