Goal:
Learn Network analysis and the various solvers within the tool.Objectives:
The objective for this exercise is to calculate the impact Frac Sand mining has on Wisconsin's roads. Since the primary method of shipping is by dump truck to rail road, the analysis will focus on trips from the sand mine to the rail road loading sites, or "rail terminals."Outline
- Load features into the Network Analysis Window
- Calculate a route
- Calculate a closest facility and route
- Build a model to calculate the closest facility route
- Claculate the cost of sand truck travel on roads by county
| Map 1 Locator map of the Counties in Wisconsin which contain a Frac Sand Mine and/or Railroad Terminal. |
Data Sets:
Railroad Terminals - Point feature classNorth America Street Network USA Dataset - Network dataset created by ESRI.
Geocoded Sand Mines - Point feature class, sand mines found and cross checked by GEOG 339 students, 120 total WI mines.
Methods:
TOOLS USED:Add Locations
Make Closest Facility Layer
Solve
Copy Features
Select Data
Project
Intersect
Summarize
Add Field
Calculate Field
The main tool used during the project was Model Builder within ArcMap. Using the search tool to quickly navigate the ArcToolbox, it was easy to find the tools needed to accomplish the various tasks. Once all the feature classes were created, all that remained was to calculate the total miles each of each trucking route per county; and, ultimately calculate the cost each county would pay for maintenance of roads per year. Model 1 shows the process of adding the various feature classes (in turquoise):
050_000 = Shapefile of Wisconsin
streets = ESRI's Street Network
Mines_AOI = Frac Sand Mines in West Central Wisconsin
Terminals_LoadingSites = Point feature class of Rail terminals & Railroad Loading Sites
| Model 1 Model of Closest Facility solver with the end output table showing cost of trucking Frac Sand across each countys' roads |
To Calculate the Trucking Cost Per County (dollars) / Year
Several assumptions were necessary:
- Each sand mine would use 50 trucks per year.
- Each truck would travel from the sand mine to the rail terminal AND back.
- The cost per truck mile is 2.2 cents.
Final Equation:
Trucking Cost = (SUM_Shape_Length x 0.000621371 x 0.022) x 100
Explaining the variables and numbers:
SUM_Shape_Length : was the total distance of all the routes in that county (map units = meters)
Conversion factor : 1 meter = 0.000621371 miles
Cost of each Truck / mile : 2.2 cents
Number of trucks / year, traveling to and from rail terminal : 100
Results:
The results were pretty straight forward. Certain roads were more highly traveled than others due to the way the road network was layed out. Unfortunately I did not record what the impedance was set to for the routing. However, I can make an informed decision based on the information in the output table. I assume, with confidence, that distance was the cost being calculated and regulating which routes were ideal. Map 2 shows the routes taken (red) from each sand mine (turquoise circles) to its respective rail terminal (mustard R&R circles).| Table 1 Shows the three statistics calculated for this exercise. |
Discussion:
Although this was a fun and interesting project, it wasn't without its flaws. First of the impact on the roads was calculated to be constant throughout the travels. In reality the trucks weigh much more on the destination trip with a full bed load of sand than they do coming back. Next, the method assumed that the truck would travel to the rail terminal AND back. I imagine that the trucks do not religiously come back to the sand mine after every delivery.
Although this was a fun and interesting project, it wasn't without its flaws. First of the impact on the roads was calculated to be constant throughout the travels. In reality the trucks weigh much more on the destination trip with a full bed load of sand than they do coming back. Next, the method assumed that the truck would travel to the rail terminal AND back. I imagine that the trucks do not religiously come back to the sand mine after every delivery.
Conclusions:
The focus of this project was to have a crash course in Network Analysis and by the end feel comfortable with the general procedure. Along the way more routine tasks had to be repeated which helped reinforce the important steps in the process; such as, adding a new solver (i.e. Closest Facility layer, or new route). Continued projects within the Network Analyst are sure to occur given the expanding field of GIS and the amount of applications and power of Network Analysis.Sources:
ESRI's Street NetworkW:\geog\ESRI\streetmap_na\data\streets



