Travel Time Cost Surface Model (TTCSM)

gorgeousvassalSoftware and s/w Development

Nov 7, 2013 (4 years and 1 month ago)

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Natural Resource Program Center

Kirk Sherrill
-

GIS Specialist

Brent
Frakes



Geographer

Stephani

Schupbach



GIS Specialist



NRPC


I&M Division


GIS Program

Fort Collins, CO



George Wright Society Conference

GIS Rapid Fire


March, 2011



TTCSM
-

SOP

Travel Time Cost Surface Model (TTCSM)

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The TTCSM:



Is a GIS Python Model which:

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Calculates travel times from defined
point(s) to other locations in an AOI


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Dynamic: User and Park Specific


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Uses readily available GIS Data




Efficient Field Data Sampling Design and
Planning



Packaged as two python scripts

Requiring only basic programming experience

Moderate GIS experience

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TTCSM is a linear model which performs
:


Cost Surface


Speed Surface


Travel Cost Surface


Travel Time Modeling



TTCSM
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Schematic

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Cost Surface

-
Represents the amount of travel speed
resistance per cell

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Generated in a simple overlay manner

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Key Steps:

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Determine desired input layers and order

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Assign Percent of Maximum Travel Speed
(PMTS) values for each data layer



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Speed Surface

-
Defines the travel speed (seconds/per meter)
per cell

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Function:

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Road Network Speed

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Trail Speed

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Hillslope

Speed

-
Trail and
Hillslope

Speed are defined using Slope
values and
Tobler’s

(1993) equation:



























05
.
0
29578
.
57
*
5
.
3
*
6
Slope
TAN
ABS
EXP
T
obler
, W. 1993. Three presentations on geographical analysis and modeling. Technical report. 93
-
1, National center for
geographic information and Analysis, University of California, Santa Barbara.

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Travel Cost Surface

-
Final Travel Speed
at which movement
in a cell occurs.




Travel Cost Surface (miles/hour) for
ROMO

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Final Step: Travel Time
Modeling

1. Traditional Cost
Distance Modeling


ArcGIS

Cost Distance
Function


Isotropic Model (treats
all directions as equal)


Travel times for a TTCSM which used Cost
Distance Modeling

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Directionality Matters
(Anisotropic)


incorporate the
influence of Slope




More Realistic User Specific
Travel Times (Upslope and
Downslope)





9 Predefined Path Distance
Scenarios


Travel Speed by Slope for five different flat
surface walking speeds when using path
distance modeling with a “linear” Path Distance
Scenario.

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2. Path Distance Modeling

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ArcGIS

Path Distance Function




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Travel Time Modeling
Output:


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Travel Time Grid(s):
Hours, Minutes, or
Seconds


Least Cost Paths


One Way or Round Trip
Least Cost Paths



Travel time least cost paths using an inverse
linear path distance travel time model

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TTCSM Summary

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Dynamic in nature to accommodate user
Specific Travel Time Modeling Needs

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Outputs Travel Time Grids and

Travel Time Least Cost Paths

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Runs in the Python Scripting Language on a
computer with
ArcGIS

9.3

-
Working on Arc10 functionality


ESRI Problem
between versions!



Scripts and SOP are Downloadable at:

http://nrinfo.nps.gov/

-

Search for “TTCSM”

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Thanks & Questions?

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