The Pontchartrain Causeway is in fact 2 parallel roadways, one for northbound traffic and the other for southbound. The southbound lane was opened in 1956 and the northbound opened in 1969. Each lane is separated by a 24m (80ft) gap and the overall result is one of fast and relatively safe travel. Across the length of the Causeway there are seven crossover areas simply to allow for emergency vehicles.
Each roadway is made up of prestressed panels that are then supported by 9,000 pilings. At roughly 2 mile intervals there are small shed like buildings on the southbound lane. These are huts made of fibreglass and house the system that keeps the Causeway lit at night. Power is taken from either side of the lake so if the power is cut on one side the transfer can happen quickly while maintaining a good level of safety on the Causeway.
Since it was first built, the Pontchartrain Causeway has caused much dispute in regards to being the longest bridge over water in the world. This claim was challenged in 2011 with the completion of the Jiaozhou Bay Bridge in Chinas Shandong province. The Guinness Book of World Records had to make a new category for bridges to include those that crossed water. The Pontchartrain Causeway is a straight roadway and is classed as a 'continuous bridge' while the Jiaozhou Bay Bridge is curved and classed as an 'aggregate bridge. It is a technical difference and one that neither the USA or China seem ready to settle upon.
Hurricane force winds and the occasional collision from barges on the lake but no damage has been caused.