Question:
R-[TIP #] is a superstreet design, 4-lane divided, that has directional crossovers with median u-turns. The grade point is at
the median edge of pavement. Based on this, how do we get the criteria to draw the concrete islands at the intersections
and u-turns?
Answer:
A new feature has been added to the Geopak Graphical Criteria database. This new feature is called Automatic Pavement
Extension, or APE for short. The main purpose for creating the APE feature of Criteria is to minimize or eliminate the
creation of independent shapes at problem areas with Geopak Shape Maker. Often, it is a time consuming effort and the
results may not necessary guarantee complete compatibility with Criteria.
There are two key locations to consider for the APE feature, Inside (Medians) and Outside (Edge of Travel Way or
Shoulders).
Whether extending the proposed pavement to the inside or outside of the template, the green proposed EOT line on level
"Prop EOT" (required) can be used to extend the proposed pavement surface and subgrade to. The proposed EOT line
must be copied in from the DSN file and place into the GGC file at the same location if one wishes to do this. Once the
finished grade has been drawn in the cross section file, in another Criteria input file, process the
Cri_FinishedConcIsland.x file and procedure to mount the concrete island on top of the finished grade.
TYPICAL APE APPLICATIONS
Bulb Type U-Turns
Median Crossovers
Left or Right Turn Lanes Approaching At-Grade Intersections
Adhering to our commitment as to make GGC very easy to use, the median APE can read a user's defined custom
superelevation rate (-0.120 ft/ft to 0.120 ft/ft) as an adhoc value. Future GGC developments may include the ability to read
the entire Project custom and standard SE rates as an text input file.
Ideally, one can simply create the Geopak shapes (blue dependent shapes) with AutoShape. Then in the area where
pavement transitions or problem areas, such as superstreet limits, and instead of creating independent shapes with Shape
Maker, use the proposed EOT line in a plan view file to define the proposed pavement limits in the cross section. The APE
module of Criteria hopefully will help alleviate some these problems and save time in the long run to create proposed cross
sections.
NC DOT
NC DOH
NC GOV
Design Quick Links
