GIS-T. GIS and Transportation. In general, topics related to GIS-T studies can be grouped into three categories: GIS-T data representations, GIS-T analysis and modeling, and GIS-T applications. . GIS-T data representations. The most common representation used is comprised of:
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GIS-T
GIS and Transportation
Source: http://www.dot.state.ia.us/gis/info_page.htm
Source: http://www.esri.com/news/arcuser/0401/topo.html
One of the weaknesses of linear referencing is that the spatial description of the event data is based on a dynamic linear network. Suppose that there is a realignment on a road that reduces the length of the road by a half mile. If the measurement attributes of the road are updated to reflect this new length, all of the ‘measure-referenced’ event data that occurs on segments “downstream” from the realignment will mysteriously move “downstream” by a half mile. This is not the desired result! If an event, such as a traffic accident, happened at a certain spot, you want it to stay there!
Source: Intergraph’s White Paper on GeoTrans: Transportation Data Model
Dynamic segmentation uses a linear referencing system to define a common datum for referencing the linear lines that the DOT would call roads. The DOT may use the mileposts to reference that system
Here, the mileposts are not shown, but each data type (speed limit, AADT, pavement type, and skid value)
is stored independently and only merged when queried upon. Notice that the resulting segments from the query
are new lengths of road that do not exist anywhere else in the data.
Source: http://www.dot.state.ia.us/gis/info_page.htm
There is obviously lots to learn about GIS-T, and we have only touched upon a very limited selection of topics. We could dedicate an entire course to the subject (and many people do!).