# Modeling a Subdivision Road Network

It is always good to take a look at using Vertical Design with different site problems. You can always see a repeat behavior requirement in these. This example from Scotland in the UK has a few good examples of the “tricks” you need to use to make it all work. It also highlights the things that you always need to look for when preparing the linework

1. The centerlines set up as linestrings - so you can easily edit them if needed - in this example where the alignments cross edge of pavement and where the alignments meet each other the elevations don’t match which will generate flags - so get those adjusted first. Also make sure that the alignments HAL and VAL elements match from a stationing / chainage perspective and make sure that the HAL and VAL are the same length and cover the same station range.
2. Join the lines together as required - typically side roads should always stop at the edge of pave of the road that they are teeing into - i.e. the curb return for the side road will start where it meets the edge of pavement of the road that crosses its end
3. The main line at each intersection should have an edge of pave line that follows the edge of pave through the intersections because you are likely to want a -2 or -2.5% cross slope on the main line through the intersection.
4. Look for roads that loop around on themselves. Remember that vertical design will not like a road that goes around a 180 degree turn. You can leave the alignments as continuous lines but the edge of pave strings will need breaking at convenient locations so that they don’t turn 180 degrees on themselves. Typically break them at the start of a curve or an end of curve section.
5. For the parking bays you want the parking bay edge of pave to stop at the edge of pavement of the main line to which it is connected.
6. You want all of your linework to touch where the end of one line meets another line i.e. the curb returns at the edge of pavement of a main line - the arc return should touch the edge of pavement line - if it doesn’t then you need to decide how you want to fix it.

If you do the above 6 things well and get them right, using vertical design to create the pavement model should be relatively straight forward.

Video Shows How To Do This

2 Likes