It's always interesting to visit the Exploratorium construction site because there are so many activities going on concurrently. When construction begins on a typical new building, the early activities often consist of moving earth and pouring concrete foundations below the ground's surface. It might be several months before you start to see a building emerge above ground. Things get going a little faster on a renovation project because you have a building already there when you start.
The Exploratorium construction site has become active and interesting even faster than the typical renovation because work is taking place inside, outside, up on the roof, in among the roof trusses, out on the pier decks, under the pier decks, in boats and barges alongside the pier decks, and even underwater all at once. When I'm on the site, I'm often reminded of the illustrations in my children's Richard Scarry books about Busytown, where every building is covered with busy townsfolk working away at their daily tasks.
The site is located on a pile-supported pier over the water, which means that a significant portion of the construction is taking place close to or under the water. The structural repair and seismic retrofit work near the water involves a lot of noisy and dusty cutting, chipping, and drilling of the surfaces of existing concrete piles and pier decks. This is followed by placement of new reinforcing steel bars, various types of formwork, and new concrete.
It's amazing how many different kinds of scaffolds, boats, barges, and other floating objects the contractors have needed to employ to gain efficient access to the work over the water. I've been surprised on several occasions to look over the edge of the deck and find that what had been a bustling area of construction a few hours ago at a lower tide was now an empty scaffold under water awaiting the next low tide for work to resume.
As a structural engineer, I tend to pay close attention to the quality-control aspects of the construction process. Although engineers rely on a variety of physical testing procedures, such as concrete cylinder compression tests or magnetic particle testing of welds, to ensure that the finished work is of good quality, one of the most important tools we have is our eyes. Visual observation of the work is a powerful tool, and the more eyes that are looking the better.
When divers perform work under murky water, the opportunities for visual observation become more limited. To surmount this challenge, we have employed underwater video cameras and in-depth training sessions that have included the divers doing the construction work, the inspectors monitoring the work, and the structural engineers.
As with many things, success in this case depends upon good communication of what is to be done by all parties. Having spent some careful effort at the beginning with cameras and discussions, the underwater work has progressed quite well ever since.
Having been closely involved with the project throughout design and construction, and having watched a tired old pier undergo such a dramatic transformation, I very much look forward to taking my children to the new Exploratorium when it is completed, both to enjoy and learn from the exhibits, as well as to share a story or two about the construction project.