Curvy roads, scored by us
The curvy-roads finder has run on a database we downloaded from someone else's site since the beginning. From today it runs on roads we score ourselves, from OpenStreetMap, for every country in the catalogue — with Germany, France and the Balkans in for the first time, every road result listed once instead of twice, and the scenic, water and elevation filters finally backed by data.
What changed for you
More roads, everywhere. Against the old database, the new one holds 77 % more "twisty" kilometres across Europe and 92 % more at the lowest preset. Germany and France go from a few hundred kilometres to 99,000 and 278,000 twisty ones; Serbia, Bosnia, Montenegro and Albania, which the old source never covered, are fully in. Only Austria comes out a shade lower at the twisty preset, and we know why.
Every result once. The old database had been loaded twice and half of it was a second copy, which is why a search used to list the same road on two consecutive lines. The new one is built with a uniqueness rule and cannot double up.
Whole roads, not fragments. A road in OpenStreetMap is drawn as many short pieces — a new piece at every junction, every change of speed limit, every village name. Scored one by one, most pieces of a twisty road fall under the threshold and vanish. We now join the pieces of a road back together first, following its road number through villages, roundabouts and the short bridge ways that used to break the chain, and cut only where a road runs dead straight for five kilometres. Luxembourg's N10, which came out as forty fragments, is one road again.
The filters mean something now. "Scenic roads only" used to return nothing: it now follows recognised tourist routes — Norway's National Tourist Routes, the Romantische Straße, the Deutsche Alpenstraße, the Stelvio, the Großglockner and about 150 others — and flags the roads that actually run along them. "Near water" was never filled in; it is, from the coastline, lakes and rivers of every country. Elevation is there for every road, from our own copy of the Copernicus 30 m terrain model, and the population-density filter covers 29 countries instead of one.
Why it took some doing
The first attempt lost up to 97 % of the twisty kilometres in some countries, and the coverage report we built for exactly this purpose said so before anything shipped. Three things had to be true before the numbers turned: score whole roads rather than map pieces, do not cap a road's length (the presets were calibrated on uncapped roads), and separate the long straight stretches so a 227 km road at twelve degrees per kilometre does not outrank a genuinely twisty ten. Each was checked against the old data country by country.
What has not changed
The presets and the offline curvature packs work as before; download the updated pack when the app offers it. The "scoring method" switch is now a rank by switch over the same roads — bends, intensity (turning per kilometre), tightness (hairpins per kilometre) or climb — instead of three separately scored databases; one of those measured how densely a road was drawn rather than how twisty it was, so it had to go. The map's curvature overlay is a separate layer and is unchanged for now.