I find bridges intriguing. There are so many different types. I guess the design depends on what you want them to do.

On a recent trip to Louisiana, I got on a bridge and drove 18 miles before coming back to dry land. The key word here is "dry," because this bridge was crossing a swamp full of trees. It was built on concrete columns that were standing in water. It appeared that a channel had been cut through the swamp along the route the bridge was to follow. Then, probably working from barges, the columns were put in place in rows on both sides of the channel. Two lanes were built on each side, and there you have it; Interstate 55. The first 18 miles going north from I-10 are a bridge. To your right is Lake Pontchartrain, but you can't see it, and on your left is Lake Maurepas which is visible for a while.

This bridge stays level the entire distance, except for a brief time when it soars high over a navigable channel connecting the two lakes. It reminds me of the causeways used to connect islands with each other or the mainland in Florida. Most causeways are roads built on long narrow dikes with one or more low bridges. Some causeways are miles long.

But I have crossed bridges that climb to a peak and then it's downhill all the way to the other side. A number of these cross rivers like the Mississippi.

Engineers discuss bridges using terms like "suspension, cantilever and truss." But to me a bridge is just a bridge.

Modern bridges have taken on a fragile look. I think they try to make them look like they are about to fall, while all the time they are really stronger. There is one of these near the north end of the Natchez Trace Parkway near Nashville. You are driving along the parkway and suddenly you cross a valley about a mile wide and hundreds of feet below.

There is a tall steel bridge in Charleston, South Carolina. It looks old. It has to be tall because big ships pass underneath, but it is so rickety looking, it scares me to death. Yet I know it has been there a long time defying gravity and hurricanes.

I have passed under a number of bridges by ship, and they are impressive from that perspective. Three that come to mind are the Bridge of the Americas that crosses the Panama Canal, the one over the mouth of Tampa Bay, and a big bridge in Vancouver, British Columbia.

I look at bridges and think about how far they have come since the first premative human crossed creek on a footlog. I wonder what this century will bring?
Howard