Comprehension check. I. Decide whether the following statements are true or false according to the text:

I. Decide whether the following statements are true or false according to the text:

1. Tower Bridge is a bridge in London, or London Bridge.

2. A traditional bridge could not be built in the second half of the 19^th century because it would cut off access to the port facilities.

3. The Tower Subway could only accommodate pedestrian traffic.

4. The evaluation of the designs didn’t provoke any controversy.

5. The central span of 200 feet (61m) between the towers is split into four equal bascules which can be raised to an angle of 36 degrees to allow river traffic to pass through.

6. Water was pumped into the accumulators by water turbines.

7. About 11, 000 tons of steel provided the framework for the towers and walkways.

8. The high-level walkways between the towers were never much used and were closed in 1910, having never been reopened.

II. Answer the following questions:

1. What was the reason of building Tower Bridge?

2. Why could not a traditional bridge be built between London Bridge and the Tower of London?

3. Who was in charge of finding a solution to the problem?

4. Was the construction of the Bridge an easy task?

5. What did Wolfe-Barry make for the bridge’s beauty?

6. The official opening ceremony was conducted by the Prince of Wales, the future King Edward VII. TO your mind, why was the opening so grand?

7. What is the purpose of the bridge’s command center?

8. How many times a year are the bascules of the bridge raised?

Text 6: George P. Coleman Bridge

Brief information:

Location: Yorktown, Virginia, USA

Completion Date: 1952 (original), 1995 (reconstruction)

Cost: $9 million (original), $76.8 million (reconstruction)

Length: 3,750 feet

Type: Movable (double swing span)

Purpose: Highway

Materials: Steel, concrete

Longest Single Span: 500 feet

Engineer(s): Parsons Brinckerhoff, Inc.

In the spring of 1995, the largest double-swing-span bridge in the United States was dismantled and replaced in only nine days. The George P. Coleman Bridge in Virginia was originally constructed in 1952 as a two-lane highway designed to carry no more than 15,000 vehicles a day. By 1995, the population around the bridge had increased so much that the structure was carrying in excess of 27,000 vehicles a day.

To make matters worse, the machinery that rotated the massive swing spans often experienced mechanical problems. In short, the bridge was a major headache. Engineers considered several designs to ease congestion -- from building a tunnel to constructing a new bridge upstream -- but the least expensive option proved to be reconstruction of the existing bridge. So between May 4 and May 13, 1995, about 2,500 feet of truss and swing spans -- complete with pavement, lightpoles, and barrier walls -- were floated in six sections over 40 miles from Norfolk, Virginia, to the bridge site. It marked the first time in engineering history that such an enormous bridge was assembled off site and floated into place.

The new four-lane bridge is three times wider than the original bridge and can now carry up to 50,000 vehicles daily.

Fast Facts:

· The George P. Coleman Bridge is the largest double-swing-span bridge in the United States and the second largest in the world.

· The new bridge weighs only 25 percent more than the original because the new spans are made of lightweight, high-strength steel.

· The two main river piers contain mechanisms that lift the swing spans to different elevations so they don’t hit each other when they rotate.

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