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Diamond interchange - Definition |
| Related Words: Access, Accord, Agency, Aisle, Alley, Ambulatory, Answer, Aperture, Arcade, Artery, Avenue, Bandy, Barter, Boomerang, Brokerage, Change, Channel |
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A typical diamond interchange. A diamond interchange is a type of road junction.
Diamond interchanges are used where a freeway crosses a minor road.
The freeway itself will be grade-separated from the minor road, a bridge
being provided for one or the other. Approaching the interchange from
either direction, an off-ramp diverges only slightly from the freeway and
runs directly across the minor road, becoming an on-ramp which returns
to the freeway in similar fashion.
The two places where the ramps meet the minor road are treated as
conventional intersections. In the United States, where this form of
interchange is very common, particularly in rural areas, traffic on the off-ramp typically faces a
stop sign at the minor road, while traffic turning onto the freeway is
unrestricted.
The diamond interchange makes more efficient use of space than most types
of freeway interchange, and avoids the interweaving traffic flows that occur
in interchanges such as the cloverleaf. But
where there is significant traffic, the two intersections within the
interchange may cause congestion and accidents, requiring additional
features such as traffic lights and extra lanes dedicated to turning
traffic. For this reason, many busier junctions that were originally serviced by diamond interchanges have since been upgraded to Parclo or SPUI interchanges.
See also
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