Argentina’s Modern Underwater Tunnel

By “Awake!” correspondent in Argentina

THE Hernandarias tunnel is the first of its kind in South America. It is a 7,864-foot tube beneath the mighty Paraná, a river longer than the Mississippi and one with a greater discharge. This tunnel was opened December 13, 1969.

The tunnel connects Santa Fe and Paraná, both capital cities of Argentine provinces. A trip that formerly could take hours is now accomplished with ease and comfort in a few minutes.

Another of the benefits that many persons speak of has been the increased tourism that the tunnel has encouraged. On both sides of the river, hotels, inns and pensions are doing business as never before. Brazil, Paraguay and Uruguay all have bus lines that use the tunnel, traveling on from there to tourist places in Argentina. In October 1970, 70,654 cars and buses passed through the tunnel.

It is common to hear people ask, “Have you seen the tunnel yet?” It was this interest that aroused my curiosity. And so when visiting a friend in Santa Fe, I looked forward to traveling through the huge underwater tube.

In a few minutes we arrive at the toll station. Cars must pay seventy-five cents. Signs tell us that the maximum speed is 60 kilometers per hour (37 miles per hour), and the minimum, 40 kilometers per hour (25 miles per hour).

Soon we are on the nearly 300-yard ramp that takes us into the tunnel. About the last third of this ramp is a zone of visual adjustment. Here diminishing light allows our eyes to adjust.

Inside the tunnel the air is fresh and pleasant, compared with the heat outside. The two-lane concrete roadway is spacious, being nearly twenty-five feet wide, and the ceiling almost fifteen feet high. The sidewalls are covered with green glazed tiles. I am very impressed by the spaciousness, luminosity and neatness of the tunnel.

Along the left wall there is a booth about every one hundred and ten yards. We see at each of these a telephone, a fire extinguisher and a hose. Along the same side is a walkway protected by a railing for the watchmen.

Soon we are in the zone of visual adjustment on the other side of the river. The trip through the tunnel has taken us about three minutes. But rather than satisfying my curiosity, it has only increased it. I determine to return.

Later, on a visitors’ tour, I learn that the ventilation system allows a total renewal of the air inside the tunnel every three or four minutes. Also, two gas analyzers indicate the accumulation of carbon monoxide all along the tunnel.

I learn, too, that in the control room fourteen television sets follow the progress of motor vehicles. In case of an emergency, drivers will receive instructions through a net of loudspeakers that are placed about every thirteen feet along the tunnel.

It is also explained that simply by picking up one of the telephones a person is put in touch with the control room. In case of a fire the twenty-four fire extinguishers and hoses are ready for use, we are told. As a security measure, tankers carrying fuel are forbidden to use the tunnel. They must continue to use the old ferryboat across the river.

I am particularly interested to learn about the construction. Thirty-six gigantic cylindrical tubes, each measuring about 215 feet long and thirty-five feet in external diameter, and one adaption tube make up the entire tunnel. On the outside, three layers of polyester resin strengthened with glass wool make the tubes waterproof.

These tubes were prepared in sets of four, floated into position, and then lowered into a trench that had been dredged in the bottom of the river. Frogmen descended and united the tubes with iron straps. When the thirty-seven tubes were secured, they formed one airtight, nearly mile-and-a-half-long unit. The dredge covered over this tube, and the riverbed looked as it did before.

Argentina’s underwater tunnel is indeed a marvel of engineering.