Types and Layouts of Interchanges

Introduction

• Overview of different types of interchanges and their layouts.

Interchange Types

1. Service Interchange

   • Connects high-speed roads (e.g., freeways) with lower-class roads.
   • Typically found between two expressways/high-speed roads.
   • Higher level of service; cars generally don’t stop.
   • Example: Roundabout before entering a service interchange.

2. Access Interchange

   • Allows access between two or more freeways, typically lower speed.
   • Focused on community access rather than just traffic movement.
   • Lower level of service; cars may need to stop.

Types of Interchanges

1. Dumbbell Interchange

• Comprises two roundabouts and one bridge structure.
• Limited modification options in the future.
• Often used as a service and access interchange.

2. Rotary (Roundabout) Interchange

• Single roundabout with ramps on either side.
• Compact design, suitable for urban areas.
• Requires two structures and hard to modify in the future.

3. Single Point Urban Interchange (SPUI)

• Has a single signal at the center for all maneuvers.
• Expensive to build (15-18 million dollars).
• Easy to modify in the future.
• Issues in developing countries due to power outages affecting traffic signals.

4. Diamond Interchange

• Two signalized junctions on either side.
• Provides higher level of service and can be modified to a dumbbell in the future.

5. Diverging Diamond Interchange

• Traffic flows are shifted to allow safer intersections.
• Efficient handling of conflict points and improved pedestrian movement.

6. Trumpet Interchange

• Consists of directional ramps and a complete loop.
• Designed for terminating one expressway into another.
• High level of service with one toll plaza.

7. Cloverleaf Interchange

• Consists of four loops and four outer ramps.
• Good for rural areas but has weaving issues.
• Can be modified to other configurations in the future.

8. Stack Interchange

• Comprises numerous directional loops and ramps stacked on one another.
• High maintenance cost; good for urban areas due to compact design.

9. Turbine Interchange

• Similar to stack but with higher level of service.
• Requires larger right-of-way; allows for high speed maneuvering.

10. Y Interchange

• Consists of two directional ramps and two outer ramps.
• Higher level of service compared to trumpet interchange.

Conclusion

• Understanding these different interchanges helps in planning and traffic management.
• Each type has specific advantages and disadvantages depending on location and traffic needs.