PRELIMINARY ROAD DESIGN
Excerpt from FE Handbook:
Road Design -- Once you have covered your planning area with settings, you must connect all the landings to the existing road system. Lay in the roads on the mylar maps that you plotted so that you can avoid hazards. You can also design multiple routes so that there are options available if something doesn't work in the field. Make sure to label every section of road with the designed grade so that it can be easily digitized and attributed when you are done. Creating and maintaining a road naming and filing system early on will help with keeping track of all of the roads.
The preliminary road design involves connecting the landings determined in the preliminary setting design with a road network. This is done through a process called pegging. We will do this in ArcView, using an aml called pegger. Important considerations include side slope, road grade, alignment, and stream crossings.
Roads built on a side slope greater than 40% must use a full bench road prism. Side casting of excess materials is not allowed on side slopes greater than 55%.
Road grades are limited to 18%, with consideration being made for adverse (uphill) grades.
Horizontal and vertical alignment must be considered. A typical minimum curve radius is 60 ft. Vertical alignment must take into consideration the maximum vertical break negotiable by the critical vehicle.
Stream crossings should be eliminated wherever possible.
Should a major stream crossing be necessary, the 1999 Washougal Bridge Project is a useful reference.
See the FE Handbook, Appendix H – Gathering Roads Data, for a detailed description of the methods involved in road pegging and digitizing. The FE Handbook can be found from the FE 450 web page .
A good road naming system is to name mainline roads with a single digit, secondary roads with double digits, tertiary roads with triple digits, etc. For example, a mainline road is named road 1. The first secondary road coming off of that road is named road 11. The next secondary road from mainline 1 is road 12. The first tertiary road coming off of secondary 12 is named road 121. There are other good naming conventions, as well. Use whatever you feel is best.
More from the FE Handbook:
Cost Analysis -- Now that your roads alternatives are in place, you need to find some way of determining which roads you would like to spend your efforts on while in the field. You will not have time to check every road so indicate which ones are the most cost effective and likely to succeed.