Road Network File: Linking Carlson Civil to SurvCE, Office to Field
Tech Tip From the President’s Desk
by Bruce Carlson
The Road Network File is one of the best examples of linking the power of Carlson Civil and the office software to the field, to SurvCE and SurvPC. The RNF file is made as a special output of the Road Network command. Its intended purpose is to provide stakeout information specifically for the complex curve returns of intersecting roads, as well as cul-de-sacs. But as we will find out, it also extends the extra power of Carlson Civil to define complex subgrades and allows stakeout of “daylight” points and subgrade breaks that are dynamically calculated in the office solution. RNF Files overcome the single surface template limitation of SurvCE and deliver multiple calculated subgrades ready for stakeout.
First, for curve returns and subdivisions, consider the example below:
There are 2 curve returns for the intersecting road and one cul-de-sac. When this road is calculated through the command Road Network, the Output Tab within Settings allows for the creation of a SurvCE RNF file that is used within the command Stake Road. Below is where the file is set in Carlson Civil, Road Network command, and below that is where it is recalled in SurvCE, Stake Road.
Be sure to select the element to stakeout, such as the first curve return shown below. You load the RNF file then select the element. Always choose the “Section File” method using RNF file.
The option N for next moves through the curve return at any desired interval, such as 10 feet (or 2 meters). So you can precisely stake any aspect of the cross section along the curve return and cul-de-sac. You pick any element desired (top of curb, back of shoulder, subgrade below curb, etc.) as shown below:
But one of the lesser known benefits of the RNF file is the staking out of complex subgrades. Templates within SurvCE are entered as a single surface. You must enter the surface as one template and the subgrade as another template. However, Carlson Civil allows for a surface and multiple subgrades, and the subgrades may have breaks in grade distinct from the surface, and the daylight catch points of the subgrades with surface slopes may involve complex math, nearly impossible to calculate and hand enter in the field . Using RNF files from Road Networks in Carlson Civil delivers all subgrade break points at any station to SurvCE. RNF files overcome the one surface limitation of SurvCE and deliver multiple subgrade surfaces from Carlson Civil to SurvCE ready for stakeout.
An example of a complex subgrade is shown below:
The surface slope itself is governed by a high-side superelevation rule: break the super at SH+4, 4 feet beyond the shoulder point. But in this example, the maximum algebraic difference for the superelevation and shoulder difference is set at 7%. This forces the high side shoulder to a 3% downhill slope, not the typical 4% slope. The daylight point where the magenta subgrade contacts the 2:1 downslope in cut is extremely difficult to calculate in the field, and would also require a distinct template at many stations for the transition to full super from normal grade. By outputting the RNF file, all surfaces are sent to the field (surface and subgrade in this example), and the staking can be conducted by RNF file, using the Section method.
After making the RNF file within Road Network, we select the subgrade and “daylight point” for the complicated subgrade intersection to surface cut slope. Road Network Files make this easy.
Stakeout then begins. Clicking Plan goes to the cross section view, where the target offset of 31.928 Left is precisely calculated, something that would be very challenging to do in the field. Clicking XSCT returns to plan view.
Use RNF files to link your office road design to your field stakeout, and take advantage of the ability of RNF files to help you stake curve returns, cul-de-sacs and complex subgrades!