Modeling Hurricane Sandy’s storm surge using Autodesk Infraworks 360 – Part 1

For those of you who love experimenting with technology, Project Boulder for InfraWorks 360 is available on Autodesk Labs, giving you the ability to create two-dimensional (2D) flood simulations alongside your immersive Infraworks 360 models. The video posted by Autodesk demonstrating the preview is definitely informative, but the dataset isn’t useful for seeing how this technology preview could be used in an urban environment. Being a New Yorker, I knew exactly the data set I wanted to use, but to test out the software I needed to come up with a scenario that could not only show Project Boulder in action but also tie-in the simulation with something quantifiable. After mulling it over, I came up with the overzealous idea of modelling Hurricane Sandy!

As you know, the effects of Hurricane Sandy on New York City’s infrastructure were considerable. Numbering among those was the East River overflowing its banks flooding large sections of Lower Manhattan, Battery Park enduring a water surge of 13.88’, the flooding of seven subway tunnels under the East River and the Ground Zero construction site. In addition, over 10 billion gallons of raw and partially treated sewage were released by the storm, 94% of which went into waters in and around New York and New Jersey . That being the case, consider waiting a couple of days after a big storm to use your Groupon to go kayaking on the Hudson!

To get started, it’s easier to visualize what Manhattan looks like when impacted by a 14 foot surge so I generated the following map (using AutoCAD Civil 3D and Adobe Photoshop). As you can see, a significant portion of Manhattan is affected. It’s scary to realize that according to research “had Sandy struck two weeks earlier or later, at the highest tides during the new moon, water levels could have been up to 17 inches higher than observed”!

Now the question became, “How could I model this in Infraworks 360?” Scouring the web, I came across the data I would need on NYC Open Data’s website. NYC Open Data is one of many online clearinghouse’s that provide GIS data free of charge. The use of that data is open to anyone looking to transform the data into something meaningful, informational and/or creative. Two fantastic examples of this are Cloud Red’s visualization of NYC street trees using tree census data and CartoDB’s NYCHenge site that allows you to see on which days the setting sun lines up with the street grids all over Manhattan, not just on Manhattanhenge.

The data I found was a digital elevation model (DEM) of New York City derived from a Light Detection and Ranging (LiDAR) scan enabling us to visualize New York City’s terrain up to a 1’ resolution. This file isn’t for the faint of heart as it weighed-in at an unzipped size of nearly 160GB (my poor SSD!). Fortunately, Infraworks allows one to set a project limit so that instead of loading the entire file I was able to just bring in the data for the area I wanted. Still, even a small segment of this file is no slouch so make sure you have a robust CPU and GPU with plenty of RAM to tackle this beast of a file. This is what the resulting Infraworks model looks like:

Again the data is a bit dated as you can tell by the World Trade Center memorial site, but for all intents and purposes it be perfect for what I wanted to do, and what I wanted to do was a full scale simulation of what happened when Hurricane Sandy’s storm surge struck lower Manhattan. And this was the result:

Perhaps simulation is too strong a word for what this actually is, so a more suiting description would be an “approximation” of the storm surge since the analysis doesn’t take into account tides, complex fluid mechanics, the geometry of the surrounding buildings etc… Nevertheless the solution, again provided by the Infraworks model and the Hydronia plug-in allowed me to see results that I could quantify and use as a basis for a preliminary design that addresses the very real problem. With this knowledge, could we as architects and engineers design something that would protect lower Manhattan from future storm surges? Part 2 of this blog will give us some more insight on how to answer that question!