Thursday, June 23, 2016

Most Talkative Bridge In The World

The Lake Pontchartrain Causeway, in addition to being a lot of concrete and steel, also has a lot of antennas sticking up here and there. Over the years the bridge has invested a lot of money into radio communications to aid motorists, communicate with marine traffic, and make things easier all the way around.

In fact, in addition to being the longest bridge in the world, it is probably "the most talkative bridge in the world," with all the different ways it uses radio to serve its customers, the motorists who drive over it everyday. And today, it has even more antennas thanks to the addition of cellular telephones and other forms of radio. 

The southern toll plaza, as it was before it was removed and tolls were collected at double the amount only at the northern toll plaza. The southern toll plaza also housed at one time the causeway commission meeting room, radio equipment and antennas as well as offices. 

Here is an article I wrote in 1994 for the magazine "National Scanning Report."  
Some of the innovations listed in the article may seem dated now, but at the time they were put into service, they were "on the cutting edge." Click on the images below to see a larger version.

Text from above article

The Most Talkative Bridge In the World

Most bridges are the strong, silent type. They don't talk much. You drive on 'em, over 'em and off 'em and nary a word. 

But the world's longest bridge is also the world's most talkative bridge since it effectively uses a variety of voice and data radio services to keep in touch with its traffic. The twin spans of the Lake Pontchartrain Causeway stretch 24 miles over open water from New Orleans to Mandeville, Louisiana, and to provide for the safety and convenience of its motorists, bridge managers have called to action several high-tech radio techniques.

The bridge has its own police force, and officers on patrol communicate with each other on UHF frequencies. As they patrol the structure, officers continually monitor Citizens Band radio Channel 12, as well. They were monitoring Channel 15, but that got too busy in the area, an official said. 

The maintenance personnel of the bridge, whose number one job is to keep the roadway clear of debris, also communicate via the radio channels.

Lake Pontchartrain, one of the largest salt water inland lakes, is home to a multitude of recreational and commercial boats; two drawbridges on the causeway have to open on occasion to allow the taller sailboats through. The drawbridge operator thus has a marine radio to communicate with the workboats and pleasure craft on Marine Channels.

But the voice communications are just a small part of the story.

Call Boxes and Cellular

In order to insure quick response to any on-bridge emergencies, the Greater New Orleans Expressway Commission (the agency that runs the bridge), many years ago installed "call boxes" at half-mile intervals all the way across the bridges. Those emergency call boxes generate a radio signal that lets bridge personnel know that assistance is needed at once.

Motorists just pull a large handle down and push a red button for police, fire or ambulance response. The act of pulling the handle down spins a generator that powers the unit, so it is all a self-contained operation. A second button "cancels" the call for help, if things turn out all right.  

The call boxes are also installed at several crossovers, which link the two spans every four miles or so, allowing cars to pull over and turn around. At central dispatch, when the signal is received from the call boxes, its exact location is identified. Help is usually on the scene within minutes. 

In mid-April, a pick up truck went off the side of the bridge in stormy weather, and thanks to the quick action of passersby pulling a call box handle, a Causeway patrolman was on the scene in a couple of minutes with a rope ladder down to the water. The victim climbed up the rope ladder by himself, and personnel were even able to rescue a briefcase full of valuables before it floated away.

Atop each call box is a bar with two high-intensity yellow warning lights. These, too, are radio controlled, and when something happens on the bridge that motorists need to watch out for, the flashing lights are activated in the vicinity of the incident. In fact, activating a call box automatically turns on the flashing lights at the six call boxes immediately before the problem area. This is especially important when fog shrouds the bridge and makes visibility a problem.

Hunter Wagner, general manager for the bridge, said that the 102 call boxes were installed 15 years ago and were a key ingredient to motorist safety for many years. Today, however, with so many cars equipped with cellular phones, reports of stalled cars are often called into the bridge office by passersby even before the motorist can pull the call box handle.

The bridge is served from both directions by two cellular phone companies who both made sure that cellular service extended the length of the structure. They are Radiophone of New Orleans and Bell South Mobility.

Message Boards

The highest profile devices, however, are 12 changeable letter message boards located facing traffic at each crossover. The "variable message signs," now 13 years old, display safety reminders, community event messages, and, whenever a problem occurs on the bridge, they spell out warnings to motorists going into the area of the problem. 

Individually-controlled by radio, the message boards are computer operated, with a variety of 34 different messages kept in memory and available at the stroke of a few keys. The messages are usually spelled out in flourescent green letters on a black background, but with a tweak of the controls, they can flip over to become flourescent orange letters on a black background for the more urgent warnings.

AM Travelers Stations

The communicative nature of the Causeway extends even beyond its toll plazas, however. Several years ago, the agency installed two low-power "travelers information" AM radio stations for the convenience of people heading towards the bridge. Today, both stations are merged into one broadcasting 24 hours a
day on 1610 AM. 

The station's range is from three to five miles from the ends of the structure. While most of the time the station plays a tape loop providing listeners with generic bridge information, it is in times of fog or
accident on the bridge that the AM station really gears up. It is used to warn approaching motorists that (1) the bridge is closed, (2) traffic is backed up or (3) wide loads ought to go another way. The station is linked by telephone lines to central control for quick message changes.

"Toll Tags"

The newest, and perhaps the most technologically-advanced, radio application is called Automatic Vehicle Identification (AVI). The Causeway is one of the few toll bridges in the world that can automatically identify and deduct a toll from cars that have pre-paid accounts in the commuter discount program. Thousands of commuters traverse the bridge each day, and instead of stopping at the toll booth to pay a dollar as everyone else does, they can now obtain a specially coded device that attaches to the inside of their windshields and are "read" by transponders as the vehicles approach the toll plazas. 

From left, a toll tag reader, drawbridge attennas, and a motorist aid call box.

The police radio communications desk

The drawbridge operators are in constant contact with radio communications and radar equipment scanning for marine traffic approaching the bridge. 


A variable message sign above the toll plaza. 

The drawbridge control booth and antennas