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Predicted Traffic Learns When to Trust Recent Roads

· 7 min read
Evgen Bodunov
Evgen Bodunov
CEO @ Globus Software
Update, October 2026

The adaptive selector described in the second half of this post stayed an experiment: the June export that used it was built and loaded into Valhalla tiles for testing, and production kept one 180-day half-life for every road. Local road time, the guard for empty windows and the 180-day half-life are what production traffic data uses today.

One edge of a motorway in eastern Germany was driven at about 120 km/h until March 2024. For the next twenty months the GPS traces on it ran at 85 to 95 km/h, and since December 2025 they are back above 120. By 3 June, the last day of our June observations, the edge had 1,503 of them, and their plain median was 99.9 km/h:

60801001201402023202420252026101.6
Weighted median 101.6 km/h from an effective 729 of 1,503 observations. Without weights: 99.9 km/h (dashed).

Each dot is one traversal, day and night together, faded by how much it counts. Our traffic data gives every road a day speed and a night speed for Valhalla, and for this road the plain median is wrong by more than 20 km/h. This post is about how much an old observation should count, and about the decisions that have to be right before that question even makes sense.

Making Valhalla Understand Monday Morning

· 7 min read
Evgen Bodunov
Evgen Bodunov
CEO @ Globus Software
Update, October 2026

The weekly profiles described here stayed an experiment and never became part of our production traffic data; later evaluations closed this line of work. Production routing uses a day speed and a night speed per road, computed in local road time with a 180-day freshness half-life, which the June post describes.

In our GPS data, German urban motorways run at 84% of their weekly average speed between seven and eight on Monday morning, and at 113% at the same hour on Sunday. This is the week of that road group: the faint line is every five-minute slot, the solid one the average over an hour.

MonTueWedThuFriSatSun80%100%120%
Monday 07:30: 84% of the cohort's average speed over the surrounding hour, 82% in this five-minute slot. Shaded: the night window.

Hover over the week to read it. The is slow too. Other groups have other weeks: lose speed for the whole working day.

Valhalla can take a curve like this for every edge of its graph and use it when a route has a departure time. In May we tried to give it one from our own GPS data. This post is about how much of such a curve the data could support.