Introduction
In 2012, Hurricane Sandy struck New York City causing massive flooding in the boroughs. Included among the many devastating effects Sandy wrought was the toll it took on NYC’s public transportation system. According to the Metropolitan Transit Authority (MTA), “the night of October 29, 2012 was a significant one in the history of New York City Transit. The storm surge racing across New York Harbor was like a special effect from a disaster movie. When the waters crashed ashore at the Battery, it spilled into the subway through hundreds of openings. Stairways, vent bays, elevators connections with other utilities – all became massive waterfalls” (2015). Nine of the 14 under-river tubes were flooded and damaged. The cost to repair, restore, and protect NYC’s public transportation system is projected to be $400 million.
Damage from Hurricane Sandy still affects daily life, for example the L train is to be shut down for reparations in 2019, reminding NYC residents on how dependent we are of our public transportation system. For this visualization I wanted to compare Hurricane Sandy’s inundation map with a worst-case scenario hurricane inundation map. I then wanted to overlay the MTA subway map onto this visualization.
Inspiration
Figure 1 demonstrates an WNYC-created map of predicted flood zones by hurricane categories. I selected this map because it seems similar to what I wanted to accomplish by comparing inundation maps.
At first glance, the map seems fairly easy to decipher. However, upon closer inspection, I wondered why the flooding area of Category 1 Hurricanes was marked with red, the most alarming color, and the flooding area of Category 5 Hurricanes was marked with bright yellow, least alarming. Also, the colors that mark Category 4 Hurricanes, a murky yellow, and Category 5 Hurricanes were very similar. Furthermore, while hot colors like red, orange, and yellow mark danger, I would have preferred an inundation map using cooler colors, since there is a natural inclination to associate the color blue with water.
Fig. 1: Flooding and Flood Zones courtesy of WNYC
I chose Figure 2 because it is a flood map that employs cool colors. The Federal Emergency Management Agency (FEMA) used a grid map to compare existing flood coverage zones versus the proposed expanded flood coverage zones.
I wish the agency had not selected gray as the color for one of its variables, since the grid map is already light gray. This poor choice of color makes it very hard to see the expanded flood coverage zone. I also expected to see the expanded flood coverage zone in the brightest color, since the purpose of the map is to show viewers how coverage might change. Having the existing flood insurance zone in bright turquoise while having the potential flood zone in a duller color seems counter-intuitive. Perhaps FEMA would not have felt the need to inundate the map with text if the coloring in the visualization had spoken for itself.
Figure 2: FEMA Federal Flood Map courtesy of Emergency Management & Safety Solutions
Figure 3 is one of my favorite maps. It shows the MTA subway map re-imagined in the style of the Washington, DC Metro map. I find this map to be very visually appealing and easy to understand. It does not have unnecessary text or symbols. Since I wanted to create a map that focused on the effects of flooding in NYC’s public transpiration system, I aimed for my MTA visualization to be similar to this one, straight-forward and color-specific by subway line.
Figure 3: Here’s The NYC Subway Map—If It Were A DC Metro Map courtesy of Gothamist
Visualization
To create the visualization for the inundation zones, I used two datasets from NYC Open Data: Sandy Inundation Zone and Hurricane Inundation Zones – Worst Case. Both of these datasets were available as geojson files, so I did not modify the sets to upload them into Carto. The upload was very successful.
From NYC DoITT Public Data, I was able to obtain three datasets: NYC Subway Line, NYC Subway Station, and NYC Subway Transfers. These datasets are hosted on Carto, which was an added bonus, and made the integration into my working map seamless.
I used Color Brewer to select the colors for the inundation zones. I used a multi-hue color scheme that suggested #a6bddb and #2b8cbe as appropriate colors. Based on my analysis of Figure 1 and Figure 2, where I confused darker shades with intensity, I wanted to assign the darker color to the worst case scenario and assign the lighter color to the Hurricane Sandy inundation zone, a Category 1 Hurricane. Even though using darker/sharper colors for the area that dominates the map can be overwhelming, I thought I could mitigate this issue by using a “cool” color like turquoise.
For the MTA subway lines data, I used #f03b20, a red shade also suggested by Color Brewer. For the subway stops, I settled on Carto’s default yellow, since I thought it contrasted well with the inundation maps cool colors and the subway line’s red color.
I then created a map key, to help users differentiate between the flooding zones. I did not assign a legend for the subway lines or the stops, since I thought the title of the map made that information obvious.
Figure 4: MTA Subway Lines at Risk of Hurricane Inundation
Even though Figure 4 showed that subway stops and lines are at risk during hurricane flooding, I could not easily identify which subway lines were affected. I then borrowed NYC DoITT Public Data’s Carto map, NYC Subway Map, and overlaid it on my map.
Figure 5: MTA Subway Lines at Risk of Hurricane Inundation
Figure 5 demonstrates which individual lines are at risks during hurricane inundations. Both of my maps illustrate how minor Hurricane Sandy’s flooding zones are compared to future major hurricanes.
Interpretation and Future Directions
While Hurricane Sandy mainly affected the MTA subway lines tunnels, which are located under/across the water, Figure 4 and 5 demonstrates how vulnerable all the subway lines and stops are across the different boroughs. For example, the L train tracks along Canarsie, Williamsburg and even the Jefferson stop in Bushwick are vulnerable, compared to Hurricane Sandy that mainly affected the L train’s Canarsie Tunnel that passes underwater between Brooklyn and Manhattan. All of the subway stops and lines that pass through lower Manhattan are vulnerable to flooding. Even the N and Q, which were not severely affected by Hurricane Sandy, would be impacted in a major flooding situation, hitting the subway lines from Long Island City to Gowanus to Gravesend.
Figure 4 and 5 demonstrate how important it is to take seriously the effects of global warming. As weather disasters that once seemed anomalous become the norm and their power becomes more severe, these types of visualizations serve as canaries in coal mines, warning us of future dangers.
To continue this study, I would propose analyzing the percent of subway stops that would be affected by worst-case scenario inundations. Analyzing the neighborhoods, schools, businesses, and populations in the worst-case scenario flooding zone would also add value to this visualization.
References
Metropolitan Transit Authority. (2015). “Superstorm Sandy: Fix&Fortify Efforts Continue.” Retrieved on November 25, 2016 from http://web.mta.info/sandy/nyct_girds.htm.