Highway files should include two kinds of waypoints.
- Required intersections.
- International border points (if applicable).
- State/subdivisional border points (if applicable and only if
in a country we have split into subdivisions, such as the US, Canada,
Mexico, the UK, Russia, etc.) .
- Visibly numbered Interstate highways, US highways, and state
highways, or the equivalent in countries besides the US.
County/local/secondary/municipal/township etc. routes are not required
points. The highway designation types to be included should be clarified
before work is begun.
- Highways intersecting at an interchange.
- Other major highways that serve regional (not only local) travelers:
- Connections to a nearby parallel expressway.
- Connections to a nearby bridge over a large creek or medium/large
river (not a small creek) large enough to noticeably restrict the number
of bridges that cross it.
- Connections to a nearby, major, public car ferry over a similarly
large creek, river, or bay, but without any other water crossing serving
as a reasonably shorter (in distance or time) alternative for crossing.
- A major unnumbered urban boulevard or arterial highway to
fill in a gap of 1.5 or more miles between visible waypoints in urban
- Road (not driveway/parking lot) to a national or state-level park, major airport, or popular tourist attraction.
- Not roads to specific businesses (malls, restaurants, parking
garages, gas stations, etc.), your relative/friend's house, minor
tourist attractions, or destinations not regularly used by regional
traveler. Most automobile travel begins and ends with local/non-regional
travel, but the our target is places a regional traveler would likely
enter/exit a road.
- Intersections to split up long segments of 10+ miles (16+ km).
Usually there are some. In some cases there are not (long freeway
sections between interchanges, highways in remote areas).
- Shaping points.
- Once the required intersections are added, look at the trace
on top of OpenStreetMap in the Waypoint Editor or in the Highway
Browser. For the Highway Browser, manually add "&highlight=1" to the
hwymap.php URL to turn on the red line. The highlight variable has a
few options with values 0, 1, and 2.
- Identify sections of the route that go outside the thick red
line overlaid on the map. This line is the same as the blue line at the 5
mi/10 km scale zoom level of the Google Maps API. Add just enough extra
shaping points to your file to re-trace the thick red line so that the
centerline of your route as shown in OpenStreetMap stays within the
line. All waypoints should be positioned on the highway. The highlight
line helps you decide if another shaping point is needed.
- If the route has sharp turns or switchbacks and adding a few
more shaping points there would significantly improve the trace,
consider adding a few more, but be conservative. Not every curve needs a
shaping point. Few curves ever need more than one shaping point.
- Prefer an intersection to act as a shaping point location
wherever possible. Shaping points that coincide with intersections
should be added as normal, visible waypoints labeled in the usual way.
- Shaping points that do not coincide with intersections should
be added as hidden points beginning with "+X" and followed by a number,
i.e., +X1, +X2, +X3, etc. The plus (+) hides the point in the Highway
Browser. The number does not matter but must make the label unique for
the highway. The Waypoint Editor uses random 6-digit numbers, like
- With some practice, you can learn to identify where most of
the needed shaping points should go on your first pass. Be careful not
to add too many shaping points, just the needed ones as described.
Properly shaped routes in non-remote areas
typically have average waypoint spacing of 1.5-2.5 miles for surface
routes and 2.0-3.0 miles for freeways, considering all visible and
hidden waypoints together. There are routes that should fall outside
those ranges, but those ranges are the norm. These averages are not
suggested spacings to aim for. When the routes are worked out according
to the above instructions, these ranges are typical of the average