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'''The practice of True Elevation is NOT observed on Freeway or Ramp segments.''' | '''The practice of True Elevation is NOT observed on Freeway or Ramp segments.''' | ||
For freeway and ramp segments please reference national guidance [[Creating and editing road segments#Road elevation|Road Elevation]] and [[Overpasses, Underpasses and Bridges]]. | |||
Revision as of 16:48, 16 September 2020
True Elevation
Wisconsin uses the concept of True Elevation on segments within the State. The use of True Elevation (TE) is to better represent segments in relationship with its surroundings/ground level. Most segments should have an elevation of ground unless they pass over another segment, waterway, or natural feature. Drivable and non-drivable segments are handled the same way with elevation.
The practice of True Elevation is NOT observed on Freeway or Ramp segments.
For freeway and ramp segments please reference national guidance Road Elevation and Overpasses, Underpasses and Bridges.
Definitions
Bridge
- Segment travels over another segment (also known as overpass)
- Segment travels over a river or body of water
- Segment artificially elevated to pass over ground level objects and natural features.
Tunnel
A tunnel is any road segment that is underground and thus the GPS reception is inconsistent.
Implementation
- Elevation of overlapping segments should be set relative to each other, with the lowest segment as Ground (unless that segment is a tunnel).
- Only elevate/lower the actual bridge/tunnel section of the road.
- Bridges should be cut at the start/end of the bridge where the land falls away. You can usually see guardrail at the start/end of the bridge section. Also the pavement type may change (Asphalt to Concrete for example).
- Do not cut segments for elevation purposes if the bridge starts/stops within 500ft(150m) of an existing junction.
- Do not create a segment less than 200 feet(60m) in length
- No need to elevate segments over every small creek or box culvert. Only elevate over significant waterways or natural features.
- Only set elevation as low/high as necessary. For example, no segment should be Elevation +2 unless it passes over another segment with Elevation +1.
- Tunneled segments shall have lower elevation, relative to ground and Tunnel should be checked.
- Only segments that are actually underground should have the negative elevation.
- Tunnels should be cut at least 15m/50ft before and after the tunnel, to allow time for the GPS to regain signal.
- The use of common sense is paramount in using True Elevation.
NOTE: If you use the Bridge tool to join segments, be aware that it raises the elevation of the joined segment. Lower the joined segment as appropriate.