diff --git a/docs/developers/build_segments.md b/docs/developers/build_segments.md
index 513fab5..79bd296 100644
--- a/docs/developers/build_segments.md
+++ b/docs/developers/build_segments.md
@@ -26,7 +26,7 @@ official BRouter segments files are the ones provided by
 [CGIAR](https://cgiarcsi.community/data/srtm-90m-digital-elevation-database-v4-1/).
 If you are working with rather small geographical extracts, you can download
 tiles manually using [this
-interface](http://srtm.csi.cgiar.org/SELECTION/inputCoord.asp) (use the
+interface](https://srtm.csi.cgiar.org/srtmdata/) (use the
 "ArcInfo ASCII" format), instead of having to ask for an access for bulk
 download of data. There is no need to unzip the downloaded files, the
 `process_pbf_planet.sh` script expects a folder with all the ZIP files inside
@@ -48,3 +48,37 @@ and set the `PLANET_FILE` variable to point to it.
 _Note:_ It is possible that you encounter an error complaining about not being
 able to run `bash^M` on Linux/Mac OS. You can fix this one by running
 `sed -i -e 's/\r$//' process_pbf_planet.sh`.
+
+
+## Run a generation for elevation data tiles
+
+To match the 5x5 OSM data grid (*.rd5) files from BRouter, there are elevation
+data in a 5x5 degree format (*.bef). At the moment (end of 2023) the naming of
+this elevation tiles follows the konvention used by srtm.csi.cgiar.org: srtm_x_y
+
+As the srtm files are only available between 60N and 60S the filenames above 60N
+contains negative values. e.g. srtm_34_-1 as a tile above srtm_34_00.
+
+Please see OSM wiki for more info on [srtm](https://wiki.openstreetmap.org/wiki/SRTM).
+
+The converter generates bef tiles from `hgt` files, `zipped hgt` files and `zipped 'ESRI' asc` files.
+
+Converter call with arguments for a single tile generation:
+
+`ElevationRasterTileConverter <srtm-filename | all> <hgt-data-dir> <srtm-output-dir> [arc seconds (1 or 3,default=3)] [hgt-fallback-data-dir]
+Samples:
+$ ... ElevationRasterTileConverter srtm_34_-1 ./srtm/hgt3sec ./srtm/srtm3_bef
+$ ... ElevationRasterTileConverter srtm_34_-1 ./srtm/hgt1sec ./srtm/srtm1_bef 1
+$ ... ElevationRasterTileConverter srtm_34_-1 ./srtm/hgt1sec ./srtm/srtm1_bef 1 ./srtm/hgt3sec
+`
+Arguments for multi file generation (world wide):
+
+`$ ... ElevationRasterTileConverter all ./srtm/hgt3sec ./srtm/srtm3_bef
+$ ... ElevationRasterTileConverter all ./srtm/hgt1sec ./srtm/srtm1_bef 1
+$ ... ElevationRasterTileConverter all ./srtm/hgt1sec ./srtm/srtm1_bef 1 ./srtm/hgt3sec
+`
+
+To use 1sec and 3sec bef tiles at rd5 generation time you need an extra parameter to the fallback folder.
+E.g.
+`$ ... PosUnifier nodes55 unodes55 bordernids.dat bordernodes.dat ../srtm/srtm1_bef ../srtm/srtm3_bef
+`