Pew Trust: How Flooding Impacts Maryland’s Transportation System

A recent study indicates that major flooding occurring outside designated flood zones is significantly affecting Maryland’s highways, bridges, tunnels, and other roadways. As a result, such flooding “interrupts daily life; delaying or blocking passage of emergency response vehicles and people trying to get to work or school.”

[Above photo by Jay Bock, Flickr.]

The study – entitled “Flooding Impacts on Maryland’s Transportation System and Users” by strategic consulting firm ICF with support from The Pew Charitable Trusts — examines how flooding affects nearly 15,000 lane miles of state-maintained roadways or roughly about 20 percent of Maryland’s overall lane mileage. The findings draw from data collected between 2006 and 2020 by the Maryland Department of Transportation.

The report’s researchers reviewed 2,771 flood-related incidents for which geospatial data was available and found that 78 percent occurred outside the 100- or 500-year flood zones mapped by the Federal Emergency Management Agency. Those incidents took place, on average, only about 0.3 miles from the mapped flood areas, but even so, the findings underscore that flooding is not limited to mapped zones.

The report also identified locations along state highways that are especially flood-prone, making them prime targets for infrastructure resilience or relocation investment. Data from the past 15 years shows clusters of flood incidents on state highways, including more than 100 locations with at least five flood events within about 1,000 feet of one another. Seven locations appear to be especially at risk, with at least 30 such incidents among them, the study found.

The report also shows how flooding disrupts travel, causes safety risks, and generates economic productivity losses, among other adverse consequences. Flooding of state-maintained roadways in Maryland accounts for weeks of traffic disruptions annually, averaging 1,582 hours or 66 days per a year. Although most flood-caused lane closures lasted less than four hours, 16 percent of all disruptions lasted longer than 12 hours.

The study found that those incidents affected, on average, more than 480,000 people annually. On top of that, economic impact of lost work time and delayed deliveries cost about $15 million per year in Maryland and totaled more than $230 million during the study period.

Each flood incident resulted in an average of about $80,000 in user delay costs, Pew’s researchers noted – considered “just a fraction” of the fiscal impact because it does not factor in other expenses, such as emergency response and infrastructure repairs.

Maryland DOT P3 Project Building Stormwater ‘Smart Ponds’

The Maryland Department of Transportation recently unveiled three “smart ponds” built via a public-private partnership or P3 stormwater control project that seeks to reduce pollutants and curb local flooding.

[Above photo by Maryland DOT] 

The agency said this “smart pond” project is the first of its kind involving a state transportation department and it involved the Maryland Department of Environment, Environmental Protection Agency, Walmart, and The Nature Conservancy.

The Maryland DOT said this “smart pond” technology – developed by Opti – uses sensors and software to monitor real-time conditions such as water level and storage volume. Then, using Internet-based weather forecasts, the system remotely operate valves that control timing and volume of water discharge from the ponds as longer retention time increases water quality by capturing more sediment and nutrients.

Thus, when rain is in the forecast, the system can automatically open valves to drain the pond prior to precipitation, the agency said – helping maximize stormwater storage efficiency and reducing downstream flooding.

“These smart ponds are another innovative way we’re working to improve the communities we serve,” explained Greg Slater, Maryland DOT secretary, in a statement. “We’re being responsible stewards of the environment while at the same time helping protect the infrastructure that supports our hard-working residents and businesses.”

The Maryland Environmental Service, The Nature Conservancy, and Opti originally signed a contract in July 2020 to retrofit three stormwater runoff ponds located at Walmart stores as “smart ponds.” Concurrently, the Maryland DOT plans to spend $3.25 million to purchase 80 acres worth of Chesapeake Bay impervious area treatment credits generated by the smart ponds at Walmart. After certification of the credits, the Maryland DOT will begin purchasing the credits this spring. 

The agency said this smart pond partnership represents the first time a state department of transportation is purchasing credits from a Water Quality Trading Program. Maryland’s program created a water quality marketplace for credits generated by pollutant reductions elsewhere in Maryland’s portion of the Chesapeake Bay watershed – offering “market-based” economic incentives for pollutant reductions. 

The cost to Maryland DOT for these new credits is about $37,500 per acre, including installation of smart pond technology and 20 years of monitoring, inspecting, operating and maintaining the ponds by The Nature Conservancy and Opti. That is significantly less than the average construction cost of $150,000 per impervious acre treated through stormwater control devices such as swales, bio-retention cells and stormwater ponds, the agency noted – and that $150,000 cost does not include operation and maintenance. Overall, the Maryland DOT said it owns about 800 ponds that could benefit from this smart pond technology. 

Nevada DOT Roadway Work Includes Floodplain Improvements

Department of Transportation launches the “next phase” of major reconstruction of Great Basin Boulevard and East Aultman Street in Ely, NV, the agency is placing a particular focus on floodplain improvements.

[Above graphic by Nevada DOT.]

First, to enhance drainage in preparation for the roadway improvements, Nevada DOT crews constructed nearly 2,300 feet of concrete drainage pipe and open drainage channel in 2020 in order to convey stormwater from near the Orson Avenue and North Street intersection to Murry Creek. The agency added in a statement that those drainage improvements will continue as part of the project in 2021 and, when coupled with Great Basin Boulevard drainage improvements slated for 2021 as well, the work is the first step toward reducing floodplain limits and associated flooding concerns.

The overall project – overseen by the Nevada DOT in partnership with the City of Ely – is to reconstruct deteriorated local roadways while also upgrading the city’s water and sewer facilities. Planned upgrades alongside the floodplain improvements include a “complete streets” concept to reconstruct sections of Aultman Street and Great Basin Boulevard and reconfigure lanes to provide a safer route for drivers, pedestrians, and bicyclists.

Real-Time Storm Force Prediction Model for Coastal Bridges

Dr. Teng Wu, Mr. Shaopeng Li, and Dr. Kallol Sett from the Institute of Bridge Engineering at University at Buffalo recently unveiled a new model to improve extreme damage “risk evaluation” for coastal bridges due to hurricane wave force and storm surge. 

That research focuses first on using a synthetic 10,000-year hurricane record, together with a deep neural network-based framework to predict surge and wave forces on the bridges located in specific areas. It then taps into the North Atlantic Coast Comprehensive Study or NACCS database – built to identify flood risk and mitigation strategies – which uses damage outcomes from 1,050 “synthetic hurricanes” to provide storm surge elevation and significant wave height predictions for pre-determined locations. 

All of that information is then used to determine the probability of bridge failure dependent on how susceptible a bridge deck is to being lifted off its foundation structure, those researchers said; an event known as “bridge deck unseating” that is highlighted in the video below:

Dr. Wu — associate professor at the University of Buffalo’s department of civil, structural, and environmental engineering – said during a recent presentation that the reason a new coastal bridge failure model is needed centers on the rising number of Americans living in coastal regions and their corresponding exposure to severe weather.

According to a 22-page report by the National Oceanic and Atmospheric Association, almost 40 percent of the United States population – some 127 million people — now live in coastal areas that are increasingly vulnerable to severe hurricanes.

For example, Hurricane Sandy, which made landfall in New Jersey in 2012, caused $70 billion worth of damage to densely developed areas in New Jersey and New York – with the damage to roads and bridges representing a large portion of that monetary loss.

Dr. Wu noted that the training of deep neural network focuses on damage to bridges due to bridge deck unseating as that is the most common occurrence during hurricane storm surge. 

Graphic image provided by the University of Buffalo

For example, during Hurricane Ike in 2008, some 53 bridges in the Houston/Galveston region suffered damage – and many of those damaged structures either were constructed of timber or were low-clearance water-crossing bridges. That’s why analyzing the type of bridge, bridge clearance, and the predicted storm surge and wave height for hurricane storm season in a particular coastal area can give valuable sustainability information and aid in risk planning and emergency response, Dr. Wu noted.

The University of Buffalo research included a case study on “simply supported” coastal bridges in New York State – a study that included a risk assessment for bridge deck unseating caused by storm surges and waves. Three different “clearances” of coastal bridges – which is the distance between the bottom of the bridge deck to the mean water level – were considered in that risk analysis, with the resulting case study looking at bridges in two different areas of the region: one close to the coastline and one in the Hudson River. 

That case study found that the annual damage rate to bridges decreases as the clearance increases, and bridges at the coastline are more vulnerable to storm surges and waves due to the larger surge/wave level, as expected. What the risk analysis framework does, explained Dr. Wu, is pinpoint where risk reduction strategies will be most effective – highlight those coastal bridges with the highest risk of damage from storms, allowing for more targeted mitigation planning. Dr. Wu added that this research can also help in emergency management disaster response by highlighting the infrastructure most at risk for damage and allowing for more focused traffic management and operations planning.

Hawaii DOT Launches Storm Water Online Learning Series for Kids

Protecting the ocean, rivers, and streams from pollution is the focus of a new online learning series for kids launched by the Hawaii Department of Transportation’s Storm Water Management Program.

[Photo courtesy of Hawaii Department of Transportation.]

The Hawaii Storm Patrol Online Learning Series teaches children – known as “keiki” in Hawaiian – about storm drain systems, how they carry rainwater off roadways to prevent flooding, and why preventing litter, debris, chemicals, and other pollutants from entering storm drains helps preserve the environment.

Photo courtesy of Hawaii DOT

The free series is available at stormwaterhawaii.com and can be viewed on a desktop, laptop, or mobile device.

The agency noted that this video series is comprised of four animated videos that explain the water cycle, how Hawaii’s storm drains work, different types of pollution, and the impact of storm water on our ocean and near shore waters. Characters from the popular Hawaii Storm Patrol: New Recruits booklet star in the series and offer tips to protect the environment.

Each video is followed by a short quiz to help young viewers retain information and students who complete the online learning series become an official recruit of the Hawaii Storm Patrol and can download a specially designed Zoom background to use for their virtual classes.

An instructor’s guide is included to help parents and teachers utilize the online learning series in a remote learning or classroom setting. “Our in-person, in-classroom storm water presentations were well received by students and teachers. Keiki now understand the importance of protecting the environment and are eager to learn how they can help,” explained Jade Butay, Hawaii DOT’s director, in a statement. “We wanted to build on the success of our in-classroom program and creating a remote learning version enables us to reach more students and expand the awareness of storm water pollution prevention.”

Iowa DOT Studies Erosion, Sediment Control Techniques

To determine the effectiveness of its erosion- and sediment-control techniques, the Iowa Department of Transportation recently teamed up with Iowa State University over two construction seasons to establish which ones worked the best and which ones needed improvement.

[Photo courtesy of Iowa Department of Transportation.]

According to an Iowa DOT blog post, Melissa Serio with the agency’s construction and materials group teamed up with Mike Perez, an Iowa State researcher, to examine alternative erosion and sediment control techniques and adaptations used successfully by other transportation agencies to see how well the Iowa DOT’s standard practices.

Some of Iowa DOT’s frequently used erosion and sediment control techniques include: fabric silt fences to slow water flow and collect sediment; porous mesh tubes (called wattles) filled with straw or other material to control storm water flow; sediment basins or small retention ponds to hold water until solid materials can settle; and rock check dams.

“While we were convinced these elements help control erosion and sediment, it wasn’t clear whether these were the most effective or whether there were other approaches that could be undertaken to achieve better or less expensive results,” Serio explained. “It was important to understand the feasibility of possible changes to practice and identify the right improvements that could be put in place at the right price.”

Photo courtesy of Iowa DOT

While some of Iowa’s existing techniques already performed well, several potential improvements became apparent over the course of the two-year study. For example, simple adjustments to silt fences included reducing the space between posts, adding wire support to the fence’s fabric backing, and cutting a notch, or weir, at the top of the fence so that overtopping of water could be directed to the most desired location.

The Iowa DOT detailed that and other improvements in its final report and technology transfer summary.

Even as the research pointed to potential new best practices, the Iowa DOT said this study “also challenged our expectations.” For example, sediment basins appeared not to be as effective a sediment control measure as had been previously thought. In fact, some data collected suggested that water leaving the basins might have more sediment than it had when entering.

“Further research in a controlled environment will provide more insight, but these initial findings are extremely valuable as we seek to maximize the effectiveness of our erosion and sediment control measures,” the agency noted. “We plan to include the most effective and cost-efficient erosion and sediment control treatments identified in this research project as part of standard road plans in the near future – mostly likely beginning the spring of 2021,” the Iowa DOT said.

State DOTs on the Front Lines of Storm Preparations

State department of transportation crews along the Gulf Coast prepared for the arrival of two potentially dangerous storms this week – highlighting the key ways state DOTs protect critical infrastructure and the residents it serves during severe weather events.

[Above photo courtesy of Louisiana DOTD.]

Crews in Texas, Louisiana, and Mississippi cleared storm drains and ditches, lowered light masts, paused highway construction projects and pre-positioned barricades, signs, and portable dams to prepare for the impact of hurricanes Marco and Laura – even as forecasts for the intensity and paths those storms changed almost hourly.

“Hurricanes are part of living here,” explained Sarah Dupre, a public information officer with the Texas Department of Transportation.

“We’re treating it just like one big storm,” added Rodney Mallet, communications director for the Louisiana Department of Transportation and Development.

Photo courtesy of Louisiana DOTD

Part of Louisiana’s preparations means removing tolls on the Louisiana Highway 1 Bridge to accommodate a mandatory evacuation of Grand Isle, the state’s only inhabited barrier island. The Louisiana DOTD also pre-positioned dozens of school buses and motor coaches in other vulnerable areas throughout south Louisiana to aid with potential evacuations.

By Sunday, Mississippi Department of Transportation crews had removed computerized traffic light controllers from major intersections south of Interstate 10 and set the traffic signals to all-flash mode, noted Katey Roh, a public information officer with the agency. That action protects the controllers from floodwaters, while the controllers “flash mode” helps move potential evacuation traffic better than allowing the signals to run on regular cycles.

Although Mississippi does not have a contraflow plan – a situation in which vehicles travelling on a main road in one direction must use lanes normally used by traffic travelling in the opposite direction – it works closely with Louisiana DOTD’s contraflow plan. That plan uses all northbound and southbound traffic lanes on Interstate 55 and Interstate 59 to evacuate the greater New Orleans area into central and north Mississippi. As of Tuesday morning, neither Louisiana nor Texas had implemented a contraflow plan.

“Contraflow is a last resort,” explained TxDOT’s Dupre. “Right now, our crews are preparing for evacuations, and we have dispatched courtesy patrols to help motorists.”

Those three state DOTs also stressed that personnel and equipment must be pre-staged in relatively safe locations to respond to the most vulnerable, low-lying areas in the wake of a storm’s passage. “The most important thing is to make sure our resources are in the right places,” Mississippi DOT’s Roh said. “We’ve been through a number of storms like this, and we know which areas tend to flood, so our first responders are ready to go.”

Colorado DOT Works to Minimize Monsoon Impact on Roadways

As state departments of transportation along the East Coast sharpen their disaster plans ahead of the peak point of the 2020 hurricane season – with mid-Atlantic and Northeastern state DOTs already grappling with flooding and high-wind damage cause by tropical storm Isaias – the Colorado Department of Transportation is deploying strategies to combat the summer monsoon season, which typically runs from mid-July until mid-September.

[Above photo courtesy of Colorado DOT.]

Monsoons – a term coined in the 19th century by the British in India to describe the big seasonal winds and heavy rainfall coming from the Bay of Bengal and Arabian Sea – can create flash flooding, mudslides, and rock falls that can severely damage affect Colorado roadways; causing major dilemmas for the traveling public and Colorado DOT maintenance crews.  

For example, a seven-day-long flood event in September 2013 left behind a path of destruction over an area of 2,380 square miles, causing $700 million in roadway damage. Colorado also endured a major rock fall event in 2016 during monsoon season that closed I-70 in the Glenwood Canyon for approximately two weeks. 

Those events encouraged state officials to take a deeper look into improving the resilience of Colorado infrastructure. As a result, the Colorado DOT and the Colorado Division Office of Federal Highway Administration worked to develop a plan to proactively identify and address vulnerabilities of the state’s roadway system to threats like flooding and landslides. 

As a part of that plan, the two agencies kick-started the I-70 Risk and Resilience or R&R pilot project August 2016; examining 450 miles of I-70 from the Utah border in the west to the Kansas border to identify the potential for future damage and roadway closures due to extreme weather-related events such as monsoons.

The R&R pilot project – completed in the fall 2017 – provided risk and resilience information for assets along I-70 and helped the Colorado DOT prioritize work at key locations where risk is high and resiliency is currently low. 

One of the areas identified as an important risk factor to road closures was culvert risk mitigation planning. Lizzie Kemp, Colorado DOT’s resiliency program manager, said that the study found flooding is the largest corridor risk when looking at user costs due to delays, with 80 percent of that risk due to minor culvert failure. 

She noted that Colorado has nearly 60,000 culverts that fall into this “minor” category – under 4 feet long – and so the agency first prioritized repairing and/or replacing such culverts found in poor condition along critical routes. To help with that prioritization effort, the agency uses a Geographical Information System or GIS-based Culvert Risk Assessment tool (created by Gerry Shisler for the Colorado DOT) that takes data available statewide and uses it to identify culverts, their condition, and whether they are located on “critical” roadways. 

The Colorado DOT found approximately 1,000 culverts across the state were in poor condition on critical routes and the agency than used that information to development and implement a three-step mitigation plan:

  • Step 1: Maintenance patrols complete an inspection of identified high-risk culverts and update the condition in the minor culvert database tool.
  • Step 2: Identify and document specific proposed mitigation actions for each culvert based on inspection, which could include replacing the culvert or making minor repairs.
  • Step 3: If replacement or repair is too costly or not possible, identify and document a specific operations plan which may include increased cleanout frequency and installation of technology to monitor hydraulic flows.

The Colorado DOT also found that minor culvert damage caused more than $94 million to roadway users from delays on the I-70 corridor alone; representing 80 percent of all user costs due to flooding.  As a result, the agency expects that preventing minor culvert failure during monsoon flooding events should save hundreds of millions in highway user delay costs across the state.

FEMA Issues COVID-19/Hurricane Response Guidance

The Federal Emergency Management Agency has issued a 59-page document that provides Federal, state, local, tribal, and territorial or SLTT officials – along with those of private sector and non-governmental organizations (NGO) – guidance on how to respond to both the COVID-19 pandemic and hurricanes simultaneously.

“As SLTT partners continue to prepare for hurricane season and other emergent incidents, emergency managers should review and adjust existing plans – including continuity of operations (COOP) plans – to account for the realities and risks of COVID-19 in their prioritization of life-saving and life-sustaining efforts,” FEMA said in the document.” All reviews and adjustments to plans should factor-in FEMA’s planned operational posture, social distancing measures, CDC [Centers for Disease Control] guidance, and SLTT public health guidance.”

To ensure that operational decisions are made at the lowest level possible, FEMA is organizing to prioritize resources and adjudicate accordingly, if needed:

  • At the incident level, Federal Coordinating Officers (FCO – in consultation with regional Administrators – will work to address incident requirements using available resources. FCOs will proactively manage and identify risks and communicate new requirements to Regional Response Coordination Center or RRCCs as they arise.
  • At the regional level, the RRCCs will coordinate with FEMA personnel deployed to SLTT emergency operation centers and adjudicate resource requests until operational control is ready to be transitioned to the FCO at the incident level, when designated, and will adjudicate resources within their area of operation and coordinate with other RRCCs and the National Response Coordination Center (NRCC) as required.
  • At the national level, the NRCC will coordinate with the regions on requirements and adjudicate resources to address national priorities.