Interchanges enable movement between two or more grade-separated roadways. Interchanges vary in size and complexity, from directional ramps connecting roadways to multiple intersections and grade-separated facilities. This chapter focuses on two-level interchanges, where an arterial either overpasses or underpasses a freeway or another arterial. This chapter covers the conventional diamond interchange, along with other alternative interchanges that offer safety and/or operational benefits. Analyzing existing interchanges for operational and safety deficiencies leads to improved decision-making in the implementation of treatments to address these issues. Due diligence on interchange planning and comparing multiple alternatives are the first steps toward preventing future issues. TxDOT is implementing the Interchange Configuration Evaluation (ICE) process to streamline the evaluation of interchange alternatives for objective and evidence-based analysis. ICE tools can be seen under

Appendix K, Sections 2 and 7

.

The purpose of this chapter is to provide information on interchange designs, the methodology behind evaluating the performance of interchanges, using the ICE process (see

Chapter 10

). and tools available for interchange analysis. The tools presented herein help evaluate alternatives based on operational and safety performance, multimodal needs, cost-benefit analysis, and other considerations. This chapter is intended to be used as a guide for engineers, planners, and stakeholders when planning or evaluating existing or future interchange projects.