Engineering flood issues from Hurricanes
To continue along with our series relating to the role engineering plays in regards to hurricanes, we look back at some of the problems that occurred during super storm Sandy that took its toll on the east coast. One of the dilemmas caused was to the New York subway systems. Although they took the initiative to shut it down prior to the storm, the effects were no less than devastating. Mass flooding of the tunnels and electrical shorts were the major damage incurred. So how does the current design of these systems play into the amount of damage that occurred, as well as what is available or in the works that would lessen these effects?
One of the reasons for the amount of damage is quite understandable. The system is old. With operations beginning in October 1904, the system has been running for over 100 years. Of course the technology developed by civil and mechanical engineers, as well as the other disciplines, have come a long way since then. The problem is the implementation of updating. With upwards of 5 million riders depending on the lines running daily, the time to shut it down for renovation as well as the cost for the renovations makes this a daunting task. One of the main issues faced because of the storm, was the amount of flooding within the tunnels. Pump technology today can allow for massive amounts of water to be pumped away more quickly than what is currently in use within the subway tunnels. Engineers also understand that pumping water from one area means it must go somewhere and in these conditions where the land above is also flooded, the availability of space in which to move it could be quite a distances away. The pumps currently installed are meant to carry out just less than 2 inches of rain water per hour, which is fine for the standard rainfall of the area. The problem this time, is that after all was said and done, the tunnels had many areas of standing water that reached in excess of 4 feet. The fact that this was mostly salt water from the ocean only increased the damage done as it does not mix well with the electrical switches and components located within the tunnels. Salt in the water will cause corrosion and the longer that the water is allowed to remain, the more corrosion damage will occur. This corrosion will also occur on the structural aspects of the tunnels, affecting the rails and support beams.
Can Engineers overcome concerns?
To overcome these obstacles, Engineers from all disciplines must work in tandem. Mechanical engineers work with civil engineers to determine the placement of pump rooms and routes in which to run the piping. They work together with electrical engineers that must find ways to develop watertight systems in which to house the electrical components and switches that are needed operate the emergency systems. Due to power outages, the water removal systems need to have their own energy generating capabilities. This is yet another obstacle to overcome, and one that must be tackled to provide efficiency as well as cost savings as there are almost 500 pumping stations located within the subway system. Technology today that was not available when the subways were first designed will allow for more cost effective and efficient ideas to come to the table. Engineers will make use of computer generated drawing (CAD) software in order to simulate the conditions and effectiveness of new designs and ideas.
At an estimated 50 billion dollars in damage occurred, and these types of storms happening more often, how do you put a price on the costs associated with rebuilding the subway systems below New York. We have seen the great engineering and structural accomplishments that tower above the ground throughout the city, but aerial looks do not show the importance of the underground infrastructure that moves its population on a daily basis. As we progress in this series of blogs, we will look further into pump technology as well as some of the energy aspects related to electrical engineering.