Local-express lanes

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View from express lanes of Interstate 270 in Columbus

Local-express lanes or collector-express lanes are a set of two same-direction one-way multi-lane roadways, usually on a freeway. The outer set, usually called local lanes or collector lanes, provide access to most or all interchanges. The inner set usually called express lanes provide for non-exiting traffic. If there are several interchanges that are close together, which is typical on urban freeways, the frequent exit and entry ramps on the freeway would have the effect of slowing down through traffic along the freeway. Separating traffic into mainline (express lane) and local (collector lane) service alleviates this problem.

Typically, as is the case with the Interstate 78 in Northern New Jersey and Highway 427 in Toronto, the express lanes are intended for traffic passing through the area and exclusively have the ramps to other freeways, while the collector lanes are designed strictly to serve interchanges within that area.

Often another main purpose of having a collector-express system is to "squeeze" two freeways into one corridor. For Highway 401 in Mississauga, the collector lanes serve primarily as the direct connectors or ramp extensions between Highway 403 and Highway 427 while the express lanes are designed for 401 "through traffic". (As usual, the collector lanes also serve the surface streets Dixie Road and Renforth Drive.) In this way, a collector-express system was used to "squeeze" Highway 403 into the existing Highway 401 corridor instead of having a separate Highway 403 alignment parallel to Highway 401.

Slip ramps or transfers usually connect the local and express lanes. If one slip ramp crosses over another, the result is known as a braid or "The Basketweave" (e.g., Highway 401, between Highway 400 and Keele Street).

The disadvantage is that a significant amount of right-of-way is required to accommodate a collector-express system, especially the collector lanes and the median barriers between the collector and express lanes. Transportation departments often design new suburban freeways with interchanges spaced far enough apart to eliminate the need for a collector-express system, and the land saved can be used for a wider median and/or extra lanes.

Highway 401 in the Greater Toronto Area, between Islington Avenue and Brock Road, has had the distinction of being the longest 12-lane collector-express system in the world since the late 1960s (approximately 66 km).

Examples are listed with major collector-express systems (that may handle over several interchanges) at the top, although smaller sizes will serve at least 2 interchanges.