# How much steel was used to build the Sydney Harbour Bridge?

To complete the construction, almost six million hand-driven rivets and 52,800 tonnes of steel (or 550,000 individual pieces of steel!) were needed, and 272,000 gallons of paint were necessary to give the bridge its initial three coats before the formal inauguration day on March 19, 1932. The final cost was estimated to be 1-1.5 billion pounds (about \$150 million in today's money).

The main span is 310 feet (95 m) from end to end, and it takes four minutes for sound waves created by a car driving across it 30 miles per hour to reach the far side.

It's been said that if you walked across the Sydney Harbour Bridge every day for an entire year, you'd cover about 50,000 miles (80,000 km).

And finally, here are two facts about the strength of steel that you probably didn't know: first, steel gets stronger as it gets colder; second, steel can only be stretched about 7% before it breaks.

After it is welded together, one half of the bridge will be completed and stored until the other half is ready to be transported to its new location. As part of its storage process, each section is coated with bitumen from oil sands to prevent corrosion. When both halves are finally joined together, they form a single structure weighing nearly 2 million kg (4 million lb).

## How many people did it take to paint the Sydney Harbour Bridge?

The bridge was erected by 1,400 employees, 16 of whom were killed in construction accidents. The work of painting the bridge has become interminable. Each coat requires around 80,000 litres (21,000 gallons) of paint, which is enough to cover an area comparable to 60 soccer fields. The current world record for covering the most square metres with one inch of paint is 2,095 m² (22,300 ft²), set by British artist Mark Wallinger in 2009.

The average price of a house in Australia is \$500,000, so the value of the work done is about \$40 million.

The total cost of the project, including land acquisition and infrastructure improvements, is estimated at \$150 million (\$1.5 billion in 2015 dollars).

It may seem like a lot of money today, but at the time it was a relatively small sum. The entire budget of the federal government was less than 5% of what was spent on the bridge.

Also worth mentioning is that the number of workers involved in its construction is very high. The actual building of the bridge required a large workforce of almost 10,000 people - this is because some of the work had to be done from above deck level, where it's difficult for tools to reach.

After it was completed in 1973, the bridge became a popular subject for artists.

## How heavy is the Auckland Harbour Bridge?

The steel girders were cleverly cantilevered throughout construction, and crews labored 33 meters below sea level to prepare the foundations for the reinforced concrete piers. The bridge is 1017 meters in length and was built with 5670 tonnes of steel, 17,160 cubic meters of concrete, and 6800 litres of paint. It took ten years to build.

The weight of the bridge is 468,000 tonnes or 91,000 barrels of oil. That's more than one million cars or about 7% of Auckland's land mass.

It's also more than any other single structure in New Zealand. The Sydney Opera House has been estimated at only two thirds as heavy as the Harbour Bridge!

The average density of the bridge is about 2 tons per square foot, which makes it less dense than water.

It's wide enough for eight lanes of traffic, and when all the lanes are filled, there's still room for a small lane of parking on either side.

The main span is 193 meters, and at its highest point is 90 meters above sea level. The bridge's overall height is 98 meters from its base to its top.

It takes nine months to construct a road bridge this size. The opening ceremony was held on March 12, 2003, and since then have had free rides available for visitors during certain times each day.

## How much did the Ben Franklin Bridge cost?

The bridge cost \$37 million to build. Stronger nickel steel was employed, and a steel cable length of 25,100 miles was stretched. The road was redecked in 1984 for \$54 million, and the bridge has been repainted many times. It currently stands at 16 lanes wide with room for another lane in each direction when traffic allows.

The new bridge was expected to last at least 100 years but now appears likely to last forever given the quality of construction used during its design and building.

It's estimated that by 2050, costs will have increased by only 5% due to inflation. That means the next time it is necessary to replace the bridge, the cost will be about \$150 million.

The longest-spanning continuous truss bridge in America, it connects Philadelphia to East Trenton across the Delaware River. The bridge also holds the record for having the largest number of people ever transported over a single span (3,750), which was set in 1987 when it was used by participants in the World's Fair in New York City.

Its main span is 1,860 feet long and consists of 838 sections of rolled steel girders connected by 42,500 bolts holding it together while standing nearly 170 feet above the river. The entire structure weighs about 730,000 tons and can bear up to six total lanes of traffic.

##### Leonard Reed

Leonard Reed is a self-taught carpenter who has been working in the construction industry for over 15 years. He started out as an apprentice but quickly progressed to become a journeyman where he learned every aspect of the trade. Recently, Leonard has been promoted to lead carpenter at his construction company where he is in charge of overseeing all the carpenter's activities and supervising other employees.