CHOOSING A SCENIC BYWAY USING SPATIAL CRITERIA Continued from page 43 2. Fill in Table 3 to indicate how the six qualities were assessed for each proposed byway. These quality assessment values are based on a 1–10 scale with 10 reflecting the highest quality so the byway with the highest score is the one you will select. For example, a byway with ratings of 7, 4, 3, 5, 9, and 1 would have a final score of 29. If you chose the byway based on the highest total score (with all qualities given equal weight), which byway would be chosen? 3. Conduct some research on these four routes. For example, Byway 4 traverses the Comanche National Grassland. This area covers over 435,000 acres of grassland that has a rich history. It has been home to dinosaurs, the Comanche Indian Tribe, cattle ranchers, and the U.S. Forest Service and encompasses the Cimarron Cutoff of the Santa Fe Trail and natural wonders including more than 257 species of birds, such as Say’s phoebes, rock wrens, in the formula box. Alternatively, click the Load button on the Field Calculator and load bywaysfinalscore.cal, the expression that has been saved in the geodatabase. Click OK to populate the FinalScore field with calculated values. 6. Which proposed byway received the highest final score, and where is it located? Symbolize the four byways using graduated symbology. Use the values in the FinalScore field to determine the thickness of the lines. What does this new map help you to do? Besides the six quality criteria, consider the amount of federal lands that the roads cross. Because the federal lands were set aside as national forests, grasslands, and national parks, the more federal lands that a proposed bypass crosses, the better candidate it will make. 7. To find out the amount of federal lands these roads cross, intersect the proposed bypasses with federal lands and save the output feature class in the geodatabase. Symbolize the proposed bypasses that intersect federal lands using a shade of blue. Which of the four proposed bypasses intersect federal lands? 8. To determine which bypasses intersect the most federal lands, access your attribute table for the new intersect layer. Select the segments with a final score of 41 (Bypass 2) using Select By Attribute or by highlighting them with the mouse in the table. Right-click the shape_length field and choose Statistics. Note the length, in meters, of the roadway. Do the same thing for each segment with a final score of 43.5 (Bypass 4) and note its length (also in meters). Fill out the table below and convert length to kilometers. Which bypass would you select based on the criteria of the length of roadway on federal lands? 9. Next, weight the less-trafficked bypasses more favorably, because you consider a large number of vehicles antithetical to the whole notion of a scenic byway. As you did earlier, select the four different byways by their FINALSCORE, one by one, summarizing on AADT, entering the mean AADT for each bypass in Table 6. Based on these numbers and your preference, which bypass should be selected? Could Calculate the new field using the weighting formula. Select all fields and operators using the mouse rather than typing in the formula box, or cut and paste the expression that has been saved as bywaysfinalscore.cal in the geodatabase. To calculate a final score, use this formula: (Scenic * 1.5) + Natural + (Historic * 3) + (Cultural * 1.5) + (Archaeological * 0.5) + (Recreational * 1.0) 4. Open the attribute table for the scenic_ byways_proposed layer and add a field. Name it FinalScore, set its type to Float, and set Allow NULL Values to Yes. Why should the FinalScore field be a floating point (i.e., with decimals) type rather than an integer type? 5. Go to Options > Clear Selection, then right-click the new FinalScore field > Field Calculator. Calculate the new field using the weighting formula. Select all fields and operators using the mouse rather than typing Quality Scenic Historic Cultural Archaeological Recreational Factor 1.5 3.0 1.5 0.5 1.0 In the scenic byways attribute table, add a field named FinalScore and set its type to Float. Also set Allow NULL Values to Yes. western meadowlarks, mourning doves, and redheaded woodpeckers. At Picketwire Canyonlands, more than 1,300 dinosaur tracks can be viewed. Prehistoric rock art, early homesteaders’ rock huts, and limestone markers can also be seen. Write a paragraph about each of the four proposed byway routes, including as many of the six byway qualities as you can in each paragraph. Based on your research, you feel that the byways should not be equally weighted but be weighted as shown in Table 4. Table 4: Weighting factors for qualities Bypass Bypass 2 Bypass 4 Length, in kilometers, of bypass that intersects federal lands Table 5: Bypasses that intersect the most federal lands 44 ArcUser Spring 2010 www.esri.com