Look into Least Cost Path. Remember just because the route is shorter does not make it best, What about the elevation of the path. Surely anything over 45 degrees is pretty hard to climb. What about a lake, how does that figure into the path. Yes these things can be done in ArcMap, usually they require a friction raster, easy to make but you have to understand what you are doing.
Here is some work I have done: It addresses a lot of your concerns. Its a long copy paste but check it. Around Q 27 gets into logging trails and classifying those trails by using the shreve ordering system. Let me know if you want the data, I might be able to get it.
1 GRG 356T �?? Digital Terrain Modeling Lab 5 �?? Least Cost Path �?? Part I Objectives: the purpose of this lab is to show you the basics of least cost path analysis, using both cost and path analysis functions. We used least cost path functions in one of our hydrologic modeling labs. Here, you will use hydrologic functions in the context of path analysis. Report: Create your report in a Word processor, insert figures when necessary or when asked to, and submit through Blackboard on or March 28 th . Answer all questions marked with a �??Q .�?� Reminder: Beginning this lab, cartographic work will count toward your grade. Background 1: Suppose you are working with biologists that are studying animal behavior. They want to find the likely path a horse would take to get to a bale of hay. Your job is to use GIS and least cost path analysis to advise biologists about the likely path the animal will take. [Yet another silly topic for a lab but my purpose is to show that least cost path has a wide range of app lications, not only transportation analysis]. Instructions: 1. Create a Lab5 folder in your H drive; open ArcCatalog and connect to your folder. 2. Download the datasets from Blackboard and extract to your folder. 3. Open ArcMap and add the raster file nlcd92. Right click on this layer �?� Properties �?� Symbology �?� Import, and select nlcd92.lyr . This is a land cover map of a portion of Colorado in 1992. Q. Describe this raster. 4. Open the file nlcd92_code.txt using Wordpad. Q. How many strip mines cells are there? 5. Make a new grid of friction costs called friction by reclassifying [see more detailed instructions below] your land c over raster. Instead of having 13 different classes, I would simplify th e classes to 6-7. Assign friction values based on your own judgment. That is, do you think it would be easier for a horse to cross a pasture or a strip mine cell? For fun, make the one category really expensive (e.g. 100 for mines). 6. Q . Write down in the table below your fric tion values for each class. Include the table and a short justif ication in your report. Land Cover / Land Use Friction Value 2 7. To reclassify your grid, use the function Reclassify and enter the new values on the right. [Hint: click on the �??U nique�?� button on the right panel]. 8. Now, load the point file hay.shp. This is the hay bale location. You�??ll run the cost distance function. This is how you use it (of course, you should read the Help Menu as well): a. Source data: hay.shp file b. Cost raster: friction c. Output raster: accost1 d. Maximum distance: (leave blank) e. Backlink: bklink1 9. Q. Examine your accumulated cost grid (accost1). Use the contour function to create isocost lines (lines representing same cost). Check the (min, max) values to choose a reasonable interval. Comment on the general aspect of the raster. Make a figure with your contours. 10. Add your horse1.shp , which shows the initial location of the first horse. Now, calculate the least cost path. Click on Spatial Analyst �?� Distance �?� Shortest Path. a. Path to: horse1.shp b. Cost distance: accost1 c. Cost direction: bklink1 d. Path type: for each cell (since our house dataset is just a point) e. Output feature: lcpath1.shp 11. Q . Examine your results, comment on the path? 12. Now, add the location of the second horse (horse2.shp ). Since the origin (bale of hay) is the same, you DO NOT HAVE to recalculate the accumulated cost or back link grids (item 8). (Why?) Repeat only step (10) using your horse2 file. Make a figure (can include both horse 1 & 2 on same figure). 13. Q . How much will �??cost�?� horse 1 & 2 to get to the hay bale, according to your GIS analysis? 14. Add the DEM dem_co. Now, you�??ll use a more complex least cost path function called Path Distance. In this analysis, we will correct for the true distance based on elevation and correct for slope (i.e . upward slope is more expensive, downward slope is less expensive). Open the function �??Path Distance�??. Again, I will show you how to use it but you should also read in Help. a. Input source data: hay.shp 3 b. Output distance raster: accdem c. Input cost raster: friction d. Input surface raster: dem_co e. Output back link: bkdem f. Vertical Parameters i. Input vertical raster: dem_co ii. Vertical factor: Linear iii. Zero Factor: 1 iv. Low cut angle: -5.000 v. High cut angle: 5.000 vi. Slope: 0.2 (do you understand why it�??s 0.2?) g. Q : Draw a graph similar to this one from the Help menu, which is using the default values, but with your new vertical parameters Comment: the slope value parameter refers to the line slope of th e factor, not terrain slope. 15. Calculate the new least cost paths for horse1 and horse2 respectively using the cost path function. Remember to use th e new accumulated an d back link grids. 16. Q. Were there noticeable differences? In which parts of the landscape did you find noticeable differences? [Hint: you may want to calculate a slope grid, color code slopes smaller than 5% and see if th e path seeks low slope terrain]. Make a map. 17. Q. If you wanted to examine only the impact of the terrain on your path, disregarding the impact of friction valu es, how would you trick the function? You can try and see if there is any substantial difference between paths. 18. Remove all your files, EXCEPT your land cover and friction grids. 19. Add the file manybales.shp . Suppose now we have fi ve different locations the horses can choose to go. We are going to use a similar function to calculate an allocation raster in addition to your accumulated cost and backlink. Open Cost Allocation and use your manybales file as the source, your friction as cost raster. Name your allocation raster baleshed, your accumulated cost raster accmany and your back link grid bkmany. Q . Examine your new accumulated cost. 20. Q. Examine your baleshed raster. What does each allocation area mean? How would you interpret these zones? [Hint: easier to answer after item (22) 4 21. Add the file manyhorses.shp. Calculate the least cost path following (10) with new path to, cost di stance and direction grid. 22. Q . Make a figure showing the horses, the bales of hay, and the allocation grid on the background. 23. Q . What are the equivalent rasters for back link and allocation in hydrologic modeling? 24. Remove all files, except your land cover raster. 25. Background 2: Suppose now you�??re working for a logging company in the same area. Your objective is to design logging trails to access commercial trees and bring them to any part of the road infras tructure already in place, which will be your origin to the least cost path analysis. 26. First, you have to create a road raster . Use the con statement in the raster calculator and assign a value of 1 to class # 23 and no value data otherwise (remember, zero is a legitimate class). Name the output grid roads . 27. Create a new friction grid (see 6 & 7) but remember: your objective now is to minimize transportation costs. Is it cheaper to transport a timber log through a bare rock or grassland cell ? Name your new friction grid friclog. Q . Include the table below in your report and a short justification for your friction values. Land Cover / Land Use Friction Value 28. Calculate the accumulative cost and the back link grid; name them acclog and bklog respectively. 29. Load your trees.shp; this file shows the location of all harvestable trees. Calculate cost path using your trees as destinations and your accumulated cost and back link grids that you calculated above. Name output logtrails. 30. Now, we will calculate what is known as �??hauling traffic�?� raster. We will use the Shreve stream order classification from hydrologic modeling. But first, we have to reclassify your bklog to match the flow direction code (see below). Name new raster fdirlog. 5 Back Link Direction Code Flow Direction Code 32. Open the function �??Stream Order�?? and enter the appropriate rasters. Name output raster haultrfc and method Shreve. 33. Q. Read your lecture notes and review how the Shreve classification works. How would you interpret each road�??s segment number in your haultrfc raster? 34. Q . Suppose you are the logging operation mana ger. Which logging trail segments would require more maintenance? Why? 35. Q . Bonus (1 pt): There are similarities between hydrologic modeling and least cost path analysis. Water fl ows to the lowest point (ori gin in LCP) in your raster DEM following steepest descent rules (almost like following cheapest route in LCP). What raster in least cost path analysis would be equivalent to the DEM? Is it the friction, accumulated cost, or the back link grid? Explain your answer. Make a 3D figure in ArcScene to illustrate your answer.
You can use the Closest Facility solver to do this. Load your 1 facility as the Incident in the closest facility layer, the 500 locations into the Facility layer and then bring up the properties of the closest facility layer and on the analysis tab in the Facilities to Find, enter 500, click ok on the properties and then solve. You will get 500 shortest path routes from the 500 locations to the 1 facility. Also note, you can choose to travel from the facility or to the facility as your application may need. More help here: