Carlson RoadNET: Adding and Editing Intersections
Intersections are created automatically in the Road Network feature without any input from the user. Once Intersections are identified, they are listed and managed in the Intersection area of the Road Network: Task Pane.
Edit: Use this button or right-click on the intersection in the project tree and choose Edit Intersection to display the Edit Intersection dialog box and make changes to the Input Data and Output Files for the selected Intersection. Other changes that can be made to the Intersection design are:
1) Changing the Primary/Secondary status of the Roads creating the Intersection,
2) Making design changes that apply to the entire Intersection,
3) Making design changes that apply to one or more Corners of the Intersection.
Reset: Use this button to overwrite all design changes made to the selected Intersection and reset to the original Intersection design.
As stated above, Intersections are created automatically in the Road Network feature without any input from the user. Road Network recognizes and calculates the Intersection using the Centerline (.CL) files associated with the Roads in the Network. If two Roads are added to the Network and they share one or more common point, an Intersection is created and displayed as an Intersection in the Road Network: Task Pane.
For all Intersections, one of the two Roads creating the Intersection will be the “Primary” Road and the other will be the “Secondary” Road. When setting grade through an Intersection, the Primary Road’s Template (.TPL) file takes priority and is used to define the cross-section. The grades of the Secondary Road will adjust to match the Primary Road. Additionally, changes to any of the Primary Road design files – such as the Profile (.PRO) file – will automatically update the affected file(s) of the Secondary Road.
Upon creation of an Intersection, the Road Network feature automatically designates one of the Roads as the Primary Road and the other as Secondary. For four-way Intersections, the first Road added to the Road Network will be deemed the Primary Road and the second Road will be Secondary. For T-Intersections, the Road going straight-through the Intersection will be deemed the Primary Road – even if it’s added to the Network after the Road that stops at the Intersection. The user can change the Primary Road designation in the Edit Intersection dialog box.
Picking the Edit button displays the Edit Intersection dialog box which has a Settings tab and, depending on the type of Intersection, 2 or 4 additional tabs – each representing one Corner of the Intersection. The Corner tabs are labeled Front-Right, Back-Right, Front-Left or Back Left. T-Intersections will have 2 tabs and 4-way Intersections will have 4 tabs.
At the top of the Settings tab, the station and elevation of the Intersection is shown for all Roads.
Primary Road: Use the radio button to specify the Primary Road of the Intersection.
Profile Transition PVI Distance: This value represents the distance beyond the edge of pavement of the Primary Road (along the Secondary Road Centerline) that the cross-slope of the Primary Road will be extended.
Profile Transition VC Length: This setting allows the user to specify the length of vertical curve to be inserted at the PVI where the extension of the Primary Road’s cross-slope and the Centerline of the Secondary Road meet.
Template ID: This is the point on the cross-section used to define the horizontal (Centerline) and vertical (Profile) alignments around the Corners of the Intersection. Also, the profile for the side road will tie into this Template ID on the main road. The Template ID may be specified as any point on the cross-section – such as edge of pavement (EP) or the back of curb (BC) – as long as it has been defined as a Template ID in all of the Template (.TPL) files used to calculate the Intersection. Type the Template ID in the text box or use the Select button to choose from a list.
Hinge Profile and 2nd ID: For the side road profile, this is an optional second point to match from the main road template.
Surface Method: See the Transition Defaults section above for details on this setting.
Transition Method: See the Transition Defaults section above for details on this setting.
Link Secondary Centerline for T-Intersection: When this option is enabled, changes to the Centerline (.CL) file of the Primary Road will, if necessary, force the Centerline of the Secondary Road to be extended or trimmed in order to keep the Intersection intact.
Note: The default value for several design criteria such as Intersection radius and length of vertical curve can be set in the Transition Defaults tab of the Road Network: Settings dialog box.
Depending on the type of Intersection (“T” or 4-way), there will be either 2 or 4 additional tabs available in this dialog box. Each of these tabs represent a Corner of the Intersection and allows the user to specify horizontal and vertical Input Data and Output Files specifically for that Corner.
Radius: Use this value to specify the radius of the curve for this Corner of the Intersection. The Intersection Template ID specified in the Intersection Settings tab of this dialog box determines the point on the cross-section being affected by this setting.
Tie to Existing: Enable this option to keep cut and fill slopes from projecting to the existing ground through the Intersection. In areas of steep cut or fill, this setting helps avoid overlapping Road and Intersection tie slopes.
Edit Profile: Pick this button to open the Input-Edit Road Profile Editor and make changes to the Profile for this Corner of the Intersection. The Intersection Template ID specified in the Intersection Settings tab of this dialog box determines the point on the cross-section being represented in the Profile Editor. See Road Network: Road Profile Editor for more Help with this feature.
Reset: Use this button to overwrite all edits to the Profile of the Corner of the Intersection and reset to the original Profile.
Edit Template Transition: Pick this button to display the Edit Intersection Transition dialog box. This allows the user to control the stations for transitioning through the Intersection from a Template on one Road to a different Template on another Road. These Transition stations only apply when the Roads in an Intersection have been assigned different Template (.TPL) files.
In the Intersection Transition Dialog Box... The Starting and Ending Stations of the Intersection transition are displayed at the top of the dialog box.
Transition Starting Station: This is the station at which the Primary Road Template ends.
Transition Ending Station: This is the station at which the Secondary Road starts.
Allow Single VC: When the difference in grade at the Intersection between the Primary Road and the Secondary Road is too severe, two intermediate PVIs must be inserted into the Profile of the Corner of the Intersection in order to properly transition from one Road to another. In some cases, the transition is possible using only one intermediate PVI in the Corner Profile. If this option is enabled and if the intersecting grades allow it, only one intermediate PVI will be inserted. If this option is not enabled, two intermediate PVIs will be inserted regardless of the intersecting grades.
Template Grade Table: Pick this button to select an existing or create a new Template Grade Table (.TGT) file defining the grades for the Corner of the Intersection. This file allows the user to define specific slopes and distances for one or more Template IDs that have been assigned in the Template (.TPL) file. The Edit button opens the Template Grade Table Editor. This Editor is the same as the one used for the Template Grade Table command. Please refer to the Help files for that command if additional assistance is needed.
“L” Intersection with Knuckle: When two centerlines connect at a right angle for an “L” intersection, there is a Use Knuckle option for the outside corner that can be used to make a knuckle bulb.
Centerline: Pick this button to output a Centerline (.CL) file representing the horizontal alignment around this Corner of the Intersection. TheIntersection Template ID specified in the Intersection Settings tab determines the point on the cross-section exported to the Centerline (.CL) file.
Profile: Pick this button to output a Profile (.PRO) file representing the vertical alignment around this Corner of the Intersection. The Intersection Template ID specified in the Intersection Settings tab determines the point on the cross-section exported to the Profile (.PRO) file.
Existing Section File: Pick this button to output an Existing Section (.SCT) file for this Corner of the Intersection.
Final Section File: Pick this button to output a Final Section (.SCT) file for this Corner of the Intersection.
Additional Transitions tab
Additional Profile Transition Distance: This option adjusts the transition PVI station on the side profile. The transition station starts as the offset of the Template ID on the main road. The cross slope of the main road is used up to the transition station. For example, if the Template ID is for edge of pavement up to the gutter pan at 11.67 and the side profile needs to match the main crown up the flow line at 13.00, then the Additional Transition Distance should be set to 1.33. Additional CL Distance (Front Main, Back Main, Left Side, Right Side):These options allow you to extend the station range of the intersection. By default the intersection station range is between the PC points where the intersection arcs begin.
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