As many of America’s oldest bridges are being demolished to make way for newer, larger bridges, it’s important to look back and understand how those bridges –and other historic buildings- came to be built prior to modern technology. Last year, a collection of 55 year old pictures from the construction of the world famous Seattle Space Needle were released to the public, shedding some interesting insight into the process of the build and the people who built it.
The Mackinac Bridge has spanned 5 miles across the Straights of Mackinac, connecting Michigan’s Lower and Upper Peninsulas for 60 years. Construction began on May 7, 1954 and the bridge was officially opened to the public on November 1, 1957. According to the Mackinac Bridge Authority (MBA), the bridge contained 931,000 tons of concrete, 3,700 tons of reinforcing steel, 4.851 million steel rivets, and 1.016 million steel bolts.
At the bridge site alone, the project employed 3,500 workers. Total cost of the bridge was around $100 million at the time, which is roughly $771 million in 2017 dollars. For comparison, the New NY Bridge, which is in the middle of replacing New York City’s Tappan Zee Bridge, is 3.1 miles in length and will cost just under $4 billion.
Money alone was not the only cost of construction for the Mackinac, however, as 5 men lost their lives on the job. As you’ll see in the video, there was little to no fall protection visible in any of the footage. Add to that the hazard of being surrounded by water and it’s no surprise that tragedies occurred. In May 2004, the Michigan Department of Transportation erected a plaque to honor the 5 men who lost their lives on-site and a sixth maintenance worker who fell from his painting platform in 1997.
The fatalities of the five men were explained in the “In Memory Of” page on the MBA’s website:
“One man died in a diving accident; one man fell in a caisson while welding; one man fell into the water and drowned; and two men fell from a temporary catwalk near the top of north tower.”
The historical video footage of the bridge construction below was shared to Youtube by MLive:
While still new in the construction industries, robots are typically designed to perform a specific task in a highly precise and efficient way, like the rebar tying robot, Tybot or the brick-laying robot Hadrian X. More recently, though, robots are being imagined as platforms for 3rd party companies to develop hardware and accessories to attach to the base robot, like the Boston Dynamics robotic dog, Spot. I recently came across a new robot, called Baubot, which hopes to one day perform tasks using every tool on a typical jobsite.