Editing Reversible lane (section)

==Separation of flows==
Some more recent implementations of reversible lanes use a [[Barrier transfer machine|movable barrier]] to establish a physical separation between allowed and disallowed lanes of travel. In some systems, a concrete barrier is moved during low-traffic periods to switch a central lane from one side of the road to another; some examples are the five-lane [[San Diego–Coronado Bridge|San Diego-Coronado Bay Bridge]] in [[San Diego, California]], the seven-lane [[Alex Fraser Bridge]] on the [[Fraser River]] in [[Metro Vancouver Regional District|Vancouver]] and the eight-lane [[Auckland Harbour Bridge]] across the [[Waitematā Harbour|Waitemata Harbour]] in [[Auckland]], New Zealand. Other systems use retractable cones or [[bollard]]s which are built into the road, or retractable fences which can divert traffic from a reversible ramp.  The two center lanes of the six-lane [[Golden Gate Bridge]] are reversible; they are southbound during morning rush hour and northbound at evening rush hour.  Prior to the installation of a movable median barrier in January 2015, they were demarcated by vertical yellow markers placed manually in sockets in the roadway.

Many urban freeways have entirely separate carriageways (and connecting ramps) to hold reversible lanes (the reversible lanes in such a configuration are often referred to as "express lanes"). Generally, traffic flows in one direction or another in such a configuration (or not at all); the carriageways are not "split" into two-lane roadways during non-rush periods.<ref name="learnthelanes">[https://www.expresslanes.com/learn-the-lanes#approximate-schedule Learn the Lanes]</ref> Typically, this sort of express lane will have fewer interchanges than the primary lanes, and many such roadways only provide onramps for inbound traffic, and offramps for outbound traffic.