Stack interchange

A fully grade-separated road junction where directional ramps connect intersecting freeways, typically across multiple levels. It lets traffic move between routes without stopping at traffic signals.

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Directional ramp: A curved connector that carries traffic between roads while preserving its direction of travel. These ramps let turning traffic cross between freeways without sharp turns or opposing flows.
Freeway: A major road designed for high-speed traffic, with access controlled through grade-separated interchanges. Stacks connect freeways while preserving their uninterrupted through movement.
Cloverstack interchange: A hybrid interchange combining directional ramps with one or more loop ramps. It reduces the number of costly flyovers while retaining some direct connections.
Right-of-way (transportation): Land legally reserved or acquired for a transportation route and its associated facilities. Large ramps and bridge approaches can require extensive land around a stack.
Judge Harry Pregerson Interchange: A large freeway interchange in Los Angeles connecting Interstate 105 with Interstate 110. Its layered ramps and transit facilities illustrate a complex urban stack.
Grade separation: The use of different elevations to keep intersecting traffic streams from crossing at the same level. Stack interchanges separate crossing freeways vertically, removing the need for signal-controlled crossings.
Turbine interchange: A multi-level junction whose curved ramps spiral around a central area to connect intersecting roads. It offers another way to handle high-volume crossings with directional ramps and fewer tight turns.
Single-point urban interchange: A grade-separated junction where traffic from opposing ramps meets at one signalized intersection. It uses fewer structures but relies on signals, unlike a fully free-flowing stack.
Induced demand: The increase in travel that can follow an expansion of transportation capacity. Added junction capacity may attract more driving and eventually renew congestion.
High Five Interchange: A multi-level freeway junction in Dallas connecting Interstate 635 and U.S. Route 75. Its extensive stacked structures demonstrate how major crossings can separate many traffic streams.