n. 四叶苜蓿形的立体道路交叉点

[ noun ]
an interchange that does not require left-hand turns
<noun.artifact>

Interchange \In`ter*change"\, n. [Cf. OF. entrechange.]
1. The act of mutually changing; the act of mutually giving
and receiving; exchange; as, the interchange of civilities
between two persons. ``Interchange of kindnesses.''
--South.

2. The mutual exchange of commodities between two persons or
countries; barter; commerce. --Howell.

3. Alternate succession; alternation; a mingling.

The interchanges of light and darkness. --Holder.

Sweet interchange
Of hill and valley, rivers, woods, and plains.
--Milton.

4. An intersection between highways, having two or more
levels and a series of connecting roadways so that traffic
on one highway may pass over or under the other highway
without crossing through the line of traffic, and vehicles
may pass from one highway to the other while traffic on
both highways continues uninterrupted. A common
interchange is the {cloverleaf}.
[PJC]


cloverleaf \cloverleaf\ n.
a highway interchange between two roads in which the
connecting road pattern resembles a four-leaf clover, and
which allows moving from one road to another without
left-hand turns. One road passes over the other, and the exit
from one highway and entrance into the second highway
proceeds from the right-hand lane in all directions.
[WordNet 1.5 +PJC]