Local–express lanes

The local–express lane system is an arrangement of carriageways within a major highway where long distance traffic can use inner express lanes with fewer interchanges compared to local traffic which use outer local lanes that have access to all interchanges. This can also be called a collector/distributor lane system within a single interchange. One of the longest examples is Highway 401 in Toronto, where highway ramps between express and local lanes cross over one another; these are commonly known as braided ramps.

Some places may have only three carriageways on the highway instead of four, utilizing one directional express lanes. They may be permanent, or they can be reversible express lanes such as in Seattle where they alternate direction.

While a local–express system and a collector/distributor system are used interchangeably, some transportation departments make a distinction between the two. In a local–express system, the inner lanes are called express lanes whereas the outer lanes are called local lanes. In a collector/distributor system, the inner lanes are called mainlines while the outer lanes are called collector/distributor lanes. Generally speaking, a local–express system will have the extra outer lanes present for a long duration of the highway, as opposed to a collector/distributor system where the extra outer lanes are only present at an interchange.

Examples
The following examples include both local–express and collector/distributor lane systems.

Example of cloverleaf interchanges
A cloverleaf interchange may have collector/distributor lane system on a freeway or expressway to handle entering and exiting traffic. Usually, this lane will begin as an entrance-only ramp initially, but it will sometimes become a main lane or possibly an exit-only lane. The purpose of this lane is to facilitate traffic to the freeway exits and from the freeway entrances.