How to Show the Speed Limit and Get Over-Speed Alerts (and Their Limits)

TL;DR

Enable Show Speed Limit to look up the road's maxspeed from OpenStreetMap, then choose a spoken alert and haptic vibration. Coverage varies by road, and where nothing is published SpeedTrace says so instead of guessing. With the feature off, the app makes no network requests.

The problem

You want a nudge when you’re over the limit, but you don’t want a navigation app, an account or a data plan to do it. And a wrong limit shown with confidence is worse than none.

Steps

  1. Settings → Speed Limit → Show Speed Limit: on.
  2. Choose Spoken Overspeed Alert (a tone and a reminder) and/or Vibrate When Over Limit.
  3. Drive. A limit sign appears on the dial when a limit is known; going over triggers the alert.

How the limit is found

SpeedTrace asks OpenStreetMap for roads near your position and picks the right one: it measures the real distance to each candidate, prefers roads running in your direction of travel, and ignores cycleways and footpaths. It re-queries after you’ve moved a meaningful distance, and lets the limit expire when you’ve left the road it came from.

When there’s no limit

OpenStreetMap doesn’t have a posted limit on every road. Where none is published, SpeedTrace shows that it doesn’t know. It never guesses.

Network and privacy

This is the only feature that uses the network. Your coordinate goes to OpenStreetMap’s Overpass service while it’s on. Turn it off and the app makes no network requests at all.

Be careful

Alerts are an aid. Variable-limit zones, roadworks and school zones may not be in the data. The sign on the road always wins.

FAQ

Where does the limit come from? OpenStreetMap’s maxspeed tag for the road you are on, fetched through the Overpass API.

Is it always right? No. Data depends on volunteers and varies by country and road; temporary and variable limits are not covered. The posted sign wins.

What is sent over the network? Your current coordinate, only while the feature is on.

Is this free? Yes. Speed limit display and alerts are free.

The app SpeedTrace →