Selected Properties for 180° On- and Off- Ramps

Synchronization

See description for the same property in Interchange Ramp Properties - Direct 90° and Direct 270°

Horizontal alignment geometry

Horizontal alignment geometry is computed by three basic methods;

• Arcs
• Spirals
• Braking curve

If any segment length is set to 0 meter (line-, arc- or spiral segments), the segment is omitted from the calculated alignment.

• Lock main highway - If No, the connection to the main highway is free and will be a result of the property values and the need of length to have a solution. If Yes, the ramp alignment is computed to be locked to a specific station along the highway (Lock length below).
• Lock length - Distance from the point of intersection to the end of the ramp on the main highway's side.
• Connect type - Select whether the connection to the secondary highway is Perpendicular (to this highway) or Parallel (to the other highway).
• Connect deflection angle - The angle of the connection in degrees; positive angles are measured clockwise.
• Connect offset (secondary highway's end) - The distance from the intersection point between the highways along the secondary highway to the perpendicular connection point.
• Line length (secondary highway's end) - The length of the line segment from the perpendicular beginning point.

Horizontal method - Arcs

• Horizontal method - If the horizontal method is set to “Arcs”, following properties will be editable for designing the geometry.
• Main radius - Main radius. Various value, are computed.
• Arc length (main highway) - Length of the beginning/ending (Off/On) radius.
• Radius (main highway) - Beginning/Ending (Off/On) radius of the ramp.

Horizontal method - Spirals

• Spiral length (secondary) - Length of the spiral segment between at perpendicular side (Main radius and Line segment).
• Main radius - Main radius. Various value, are computed.
• Spiral length (main highway) - Length of the spiral segment between at highway side (Radius center and Radius main highway).
• Arc length (main highway) - Length of the beginning/ending (Off/On) radius.
• Radius (main highway) - Beginning/Ending (Off/On) radius of the ramp.

Horizontal method - Braking curve

• Spiral length (secondary) - Length of the spiral segment between at perpendicular side (Main radius and Line segment).
• Main radius - Main radius. Various value, are computed.
• Spiral length (braking curve) - Length of the spiral segment between Main radius and Braking radius.
• Braking radius - Radius at braking point between two spirals (between “Spiral length main highway” and “Spiral length braking curve”).
• Spiral length (main highway) - Length of the spiral segment between at highway side (Braking radius and Radius main highway).
• Arc length (main highway) - Length of the beginning/ending (Off/On) radius.
• Radius (main highway) - Beginning/Ending (Off/On) radius of the ramp.

Deceleration/Merging area

See description for the same property in Interchange Ramp Properties - Direct 90° and Direct 270°

Vertical alignment geometry

See description for the same property in Interchange Ramp Properties - Direct 90° and Direct 270°

Derived geometry

See description for the same property in Interchange Ramp Properties - Direct 90° and Direct 270°

Not all properties used to compute derived geometry is used when computing D shaped ramps. Dependent on what type – ON or OFF, some of the properties will be omitted.

• ON ramp - Properties at enter area are used (Exit properties not used)
• OFF ramp - Properties at exit area are used (Enter properties not used)

Merging area

• Distance A - Offset value at point A (see Illustration Merging area).
• Nose length A-B - Nose length between point A and B.
• Distance B - Offset value at point B (see Illustration Merging area).
• Length B-C - Length between point B and C.
• Distance C - Offset value at point C (see Illustration Merging area).
• Length C-D - Length between point C and D.
• Distance D - Offset value at point D (see Illustration Merging area).
• End taper length - Split length (end taper length) at end of merging area.