Barrier transfer machine

A barrier being moved on the Golden Gate Bridge
Linkage of moveable barriers[1]
This large machine was used on the Auckland Harbour Bridge to shift the center lane back and forth to accommodate rush hour traffic.

Barrier transfer machines, also known as zipper machines or road zipper, are heavy vehicles used to transfer concrete lane dividers, which are used to relieve traffic congestion during rush hours.

The vehicle contains an S-shaped channel in its undercarriage which lifts the barrier segments (which may weigh over 1,000 pounds (454 kg)) off the road surface and transfers them over to the other side of the lane, reallocating traffic lanes to accommodate increased traffic for the currently dominant (peak) direction. These barriers are linked together with steel connectors to create a sturdy but flexible safety barrier.[2]

Moveable barriers are in permanent use in such cities as Auckland (Auckland Harbour Bridge); Montreal, Quebec; Philadelphia, Pennsylvania; the New York metropolitan area (notably the Tappan Zee Bridge and the western portion of the Long Island Expressway); Honolulu, Hawaii; San Juan, Puerto Rico; Boston, Massachusetts (for the Southeast Expressway); Washington, DC; Dallas, Texas; San Francisco (on the Golden Gate Bridge and Presidio Parkway); San Diego, California; and Sydney, New South Wales; many other cities use them temporarily during construction work.

A variant of the machine uses two narrower machines running in tandem. This setup tends to be used in reversible lanes (also known as contraflow lanes) when the movable barrier is used to divide two directions of traffic—the narrower machines are less of an impediment to traffic in either direction. The lanes created by the machine are sometimes referred to as zipper lanes.

See also

References

  1. ↑ "Moveable Concrete Barrier" (PDF). p. 7. Retrieved 16 August 2014.
  2. ↑ A zipper machine in action on I-95.
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