The Causeway The Lake Pontchartrain Causeway is the longest highway bridge over water in the entire world, spanning 23.9 miles from Metairie on the South Shore to St. Tammany Parish on the North Shore.  The original span opened to the public over 40 years ago in 1956 as a two way, two lane bridge.  In 1969 a second two lane span opened, substantially increasing the bridge's safety when each span became a one way, two lane route for many commuters.  The parallel spans are 80 feet apart and seven crossovers connect the spans for use as pull-over areas for auto emergencies.  Each span has a road width of 28 feet. Over 30,000 cars cross the Causeway bridge each workday and the Causeway Commission is constantly striving to make the bridge safer for  motorists. Fog, cross winds, and thunderstorms can present particular hazards for  drivers who cross the spans. Motorists must occasionally convoy in limited groups at a reduced speed when visibility is particularly poor.   Under adverse conditions Causeway users can listen to current information about the bridge or driving conditions on Causeway Information Radio at 1610 am as they cross and approach the bridge.  Cellular phone users or citizen band radio operators can report hazardous conditions or unsafe drivers by making a toll free cellular call to the causeway police at 835-3116 or by transmitting on channel 15 on a C.B. radio.  Emergency call boxes are located on each span approximately 3BD miles apart in case of accident, mechanical breakdown or other emergency. The $3.00 Toll. The Causeway Commission now only collects a $3.00 toll on one side of the bridge in one direction. Although the Causeway Commission previously maintained offices and toll booths on each side of the Lake Pontchartrain, on May 5, 1999 the Metairie south shore booths were taken out of service and the $1.50 toll was eliminated to reduce traffic congestion on the south shore's Causeway Boulevard.  However, the north shore toll charge was doubled from $1.50 to a total fee of $3.00 to cross the bridge in a southerly direction only (heading from the north shore toward Metairie), to make up for the elimination of the north bound toll. Lake Pontchartrain is the largest inland estuary in the United States. Technically this 610 square mile body of water is an estuary, not a lake, because it connects to the Mississippi Sound and has salt-water content.