Do It Yourself! Continued from page 53 Select Features tool, highlight two or more continuous segments that make up a ramp in this area. Do not select any line segments that cross the ramp segments being selected. Zoom in to make certain all segments for that section of ramp are selected. Select elements by beginning at one end of a section of continuous segments and select them in the direction of travel. In the Editing toolbar, click the Editor drop-down and select Merge. Explore the Merge list and verify that all segments have the same source name. If the Merge dialog box contains more than one feature name, cancel the task and reselect the segments. Click OK to merge the segments and inspect the results. There should be only one arrowhead, pointing onto I-10 in an easterly direction. Continue the process of merging line segments for all ramps that cross in this interchange, including freeway roadways and ramps. If incorrect segments are accidentally merged, immediately use the Undo button on the standard toolbar to correct this problem. Zoom in and pan as necessary and save the map document frequently. When all crossing freeway and ramp segments in the I-10/I-210 interchange have been merged to form single crossing elements, follow the rest of I-10 and I-210 and merge all these segments also to create single crossing elements. Watch the directional arrow and the red endpoint symbol while merging segments. If an endpoint lands in the middle of a merged segment, undo the merge, check directionality, and change the segment selected in the Merge dialog box. If segments in an interchange contain speed limit changes, merge only segments with the same speed limit. Remember not to merge any segments across valid limited-access intersections. Undo the selection immediately to correct any accidental merges. Advanced users can use the Split tool to disconnect segments when needed. After completing all merging operations, inspect all freeway lands and ramps. Several ramps are problematic. It is difficult to tell if the feature being merged is part of an interchange or part of a crossing relationship. (Imagine how helpful high-resolution imagery would be.) When finished, stop editing, save edits, and save the map document. Now, length for all Redlands streets can be calculated and OneWay attributes can be assigned. Editing Attributes Now segment lengths and travel times can be calculated and directionality codes assigned to the OneWay field. ArcUser Summer 2009 Carefully position the mouse cursor tip near the line's midpoint. (Hint: Look for the small x.) Right-click and select Flip from the context menu. Watch as the red leading node swaps ends, indicating that the line has reversed direction. A properly oriented network www.esri.com