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Fathom data reveals hidden flood risks across Washington D.C. transportation system 

Fathom data reveals hidden flood risks across Washington D.C. transportation system 

Fathom’s US Flood Map provides a comprehensive view, highlighting an increased risk to critical infrastructure. 

A new regional flood risk assessment has revealed that the Washington metropolitan area’s transportation system is far more vulnerable to flooding than previously understood. This new analysis found 40% of roads, 64% of rail lines and 11% of bus stops across the region are at risk of flooding. Analysis completed in 2023 only identified 14% of roads, 39% of rail lines and 4% of bus stops as being vulnerable to flooding. 

Bridging the gaps in federal flood maps 

Building on FEMA’s flood maps, ICF, a leading global solutions and technology provider, and Fathom, a water risk intelligence firm, leveraged the latest technology and data analytics to develop a comprehensive inland flood model of risks across transportation assets, now and in the future. 

The National Capital Region Transportation Planning Board (TPB), housed and staffed by the Metropolitan Washington Council of Governments (COG), is the metropolitan planning organization for the metropolitan Washington region. TPB worked with ICF, which led the validation of Fathom’s US Flood Map during the procurement process and developed the technical scoring approach to assess the TPB region’s risk to urban flooding. Fathom was chosen for its accuracy and expertise in urban flood modeling, enabling TPB to build a more complete and forward-looking picture of risk. 

Katherine Rainone, Transportation Resilience Planner at TPB, said: “We’re excited to provide our member localities and agencies with a broader understanding of what transportation assets in the region are at risk to inland flooding. This information can help empower regional planners to evaluate and prioritize resilience investments and transportation projects across multiple future scenarios and planning horizons for better decision-making, as well as strengthen emergency services and overall preparedness.” 

Mason Fried, Director of Climate Science at ICF, commented: 

“We’re proud to have led the technical analysis behind this forward-looking flood assessment in partnership with TPB and Fathom to inform transportation planning and decision-making. Fathom’s data provided critical insights into how future fluvial and pluvial flooding could reshape risk across the TPB region.” 

Fathom’s US Flood Map is the most comprehensive and technologically advanced map available, filling critical data gaps to support smarter planning and climate resilience. 

Gavin Lewis, Head of Engineering at Fathom, commented: “We were delighted to be selected for this project following a rigorous evaluation by ICF. It made innovative use of Fathom’s maps and data to assess flood risk in the Washington DC area and we established an excellent working partnership with TPB and ICF. 

“The analysis brought a new perspective to river and flash flood risk locally, highlighting increased exposure across the region and providing detailed evidence for future investment decisions. It begs the question: if there is such a disparity in the data in one relatively small area, how much potentially catastrophic flood risk is being missed across the nation, and how do we close the knowledge gap?” 

Key findings 

When combining Fathom and FEMA data, the TPB found that: 

  • Roads and highways: 25 percentage point increase in lane miles at risk, from ~14% to ~39% of total, compared to FEMA data. 
  • Bus stops: 7 percentage point increase, from ~4% to ~11% at risk. 
  • Rail stops: 14 percentage point increase, from ~7% to ~21% at risk. 
  • Rail lines: 25 percentage point increase, from ~39% to ~64% of total rail miles. 

About Fathom

Founded in 2013, Fathom gives risk management professionals the most scientifically robust tools and intelligence to understand the climate’s impact on water risk. By publishing cutting-edge peer-reviewed academic research and applying it to real-world challenges, Fathom powers better decision-making for (re)insurance, civil engineering, corporate risk, financial markets, disaster response and government. 

Fathom’s dedicated team of scientists harness their passion for innovation and the environment to develop rigorous catastrophe models and comprehensive mapping and geospatial data that make a real-world difference to customers and communities worldwide. 

The US Flood Map launched by Fathom in 2023 is the most comprehensive available. It has been utilized by planners and engineers across multiple states, including Texas, Florida and Virginia, while its 2025 US Flood Risk Index highlights state-by-state risk.