Exercise 3: Adding a Turn Slip Lane to a Roundabout

In this exercise, you create the geometry for a turn slip lane, which allows vehicles to bypass the roundabout and turn from one approach road to another.

Select the entry and exit approach roads

1. Open Roundabout-Slip Lane-Add.dwg.
2. Click Home tab Create Design panel Intersections drop-down Add Turn Slip Lane  Find.
3. For the Entry Approach road, click the Approach_SN (1) alignment.
   
4. For the Exit Approach road, click the Approach_EW alignment.
   

Specify the slip lane parameters

1. In the Draw Slip Lane dialog box, under Slip Lane Parameters, specify the following parameters:
   • Segmentation Line Length: 1
   • Length of Deceleration Lane: 20
   • Length of Acceleration Lane: 10
   • Lane Width: 4
   • Radius: 50
   • Taper Length: 20
2. Under Draw Pavement Markings, specify the following parameters:
   • Outer Edge: Selected; Continuous
   • Decelerating Transition Line: Cleared
   • Accelerating Transition Line: Cleared
3. Specify the alignment properties:
   • Alignment Style: Roundabout - Slip Lane
   • Alignment Layer: 0
   • Alignment Label Set: Roundabout - Slip Lane
   • Alignment Name Prefix: SlipLane
4. Click OK.
   The slip lane is displayed in the drawing.