RSAP Frequently Asked Questions
    Input Questions
On Highway tab, can access density refer to number of driveways, for example?
Yes, that is exactly what the access density is used for.  In general, driveways, commercial entrances and minor roadway intersections can be counted as access points.  In the case of intersections, RSAPv3 is only valid on segments without intersections but if the mainline segments being analyzed are through lanes and the intersecting streets are stop-sign controlled the intersecting streets should be counted as access points.
For the highway characteristics - Do you need to put them all in or just ones that differ from the default?
You only need to enter the characteristics that are different than the default values. 
Where can I find the encroachment type abbreviations listed n the Feature report?
They correspond to the check boxes on the Analyze tab if you click the “See Settings” button.  P=primary, O=opposing, L=left and R=right so PL are primary left encroachments and OR are opposing right encroachments, etc.
The Highway tab allows entering % traffic encroaching right.  Is there a way to enter % encroaching left?  Also, please explain the encroachment adjustment factor?
The percent encroaching left and the percent encroaching right must equal 100% so you only need to specify one (i.e., the percent encroaching right).  The User Encroachment Adjustment Factor allows you to artificially increase or decrease the encroachments.  The default is 1.  If you entered 0.9 it would use 90% of the RSAPv3 prediction.  It is included in order to provide a way to calibrate RSAPv3 to local data.  Both of these input features (i.e., percent encroaching right and the user encroachment adjustment) should normally NOT be used and should be used with extreme caution when they are used.
Once you change a x-section, does the revised x-section apply to other runs? In other words, will an "All Flat" x-section be redefined to having 6:1 slopes as a default?
Any changes you make in the workbook will only affect the results in the workbook you are working on.  Changing something in the current workbook does not change any results in previous workbooks.
Is there a minimum recommended segment length?
RSAPv3 actually segments the project for you so you do not really need to worry about what the segment lengths are.  You just enter the highway characteristics by station and then RSAPv3 will chop it into appropriate homogeneous segments.  That said, however, it is not a good idea to have a lot of small segments since it will increase the analysis time – it will work ok but it will take longer.  For example, say the lane width changes from 12 to 11 at station 10+50 and a vertical grade begins at station 10+52.  RSAP would put a 2-ft long segment between 10+50 and 10+52 but you would get essentially the same results if you made both the lane width change and the grade change at the same station.