Travel Time Cost Surface Model: Standard Operating Procedure
Sherrill KR, Frakes B, Schupbach S. 2010. Travel Time Cost Surface Model: Standard Operating Procedure. Natural Resource Report. NPS/NRPC/IMD/NRR—2010/238. Natural Resources Program Center. Fort Collins, Colorado
This document presents a travel time cost surface model (TTCSM) which calculates travel time from defined point and/or linear locations to other locations within a user-defined area of interest (AOI). The TTCSM is designed to model travel time in national park units using readily available geospatial products such as road, trail, and stream networks, digital elevation models and land cover data to name a few. Outputs from the TTCSM are point -to-point specific travel time least cost paths (i.e. the modeled fastest path(s)) and raster maps in which each cell value is the modeled time required to reach the given cell from the specified starting point(s).In order to derive accurate travel time estimates, the TTCSM is intended to be dynamic in nature with the ability to accommodate user (e.g., hiker / skier / ATVer / etc.), temporal (e. g. winter / summer data collection) and park specific needs. The essence of the TTCSM is deriving a meaningful travel cost surface. Travel cost is a function of the user-defined and derived cost and speed surfaces. The cost surface defines the weight or impedance of traveling through a cell, while the speed surface defines the speed at which movement within the cell occurs. Speed is a function of the user-defined average walking speed and slope, except on the road network where speed is equal to the defined road speed limit. Using the derived travel cost surface, travel time calculations are performed using either traditional cost distance or more robust path distance modeling methods.The TTCSM is intended to be used as a tool to facilitate more efficient field data sampling design and planning. Currently, the TTCSM is packaged as a python script requiring only basic understanding of python programming, and a moderate level of proficiency in GIS.In addition to the CSM, we have included a simple model builder tool (v9.3) that can calculate stream order. This tool allows you to take any shapefile of a stream network and calculate stream order. It has has additional functionality beyond what ESRI offers since it does not require that the shapefile have flow direction. In addition, it is relatively robust in handling such irregularities as braided streams.
- Type
- Published Report
- Authors
- Sherrill, Kirk; Frakes, Brent; Schupbach, Stephani
- Date of Issue
- 2010-09
- Publisher
- Natural Resources Program Center
- Units
- IMD
- Keywords
- Cost Distance, Cost Surface, Least Cost Path Modeling, Path Distance, Travel Time, Travel Time Cost Surface Modeling, Travel Time Modeling