Examples and Precedents


Washington National Cathedral Underground ParkingRome Underground Bus ParkingSt. Peter's in Rome Underground Bus and Car Parking

Major tourist destinations around the world have worked to protect their historic sites while accommodating those who seek to visit these landmarks by creating underground parking facilities such as the National Mall Underground. In the United States, examples include Millennium Park in Chicago, Boston’s Post Office Square, and Washington, DC’s National Cathedral.  In Europe, sensitive historic pilgrimage sites including the Vatican in Rome and the medieval city of Bruges, Belgium, provide visitors with underground parking options.


The multi-purpose flood control/parking function of the National Mall Underground has a few precedents. Project architect Arthur Cotton Moore FAIA already has designed a dual-purpose underground parking/flood control facility at Washington Harbour in Washington’s Georgetown neighborhood. Rotterdam has an underground dual function parking garage/stormwater facility serving its museum district. The Smart Tunnel in Kuala Lumpur, Malaysia, solves traffic congestion and flooding problems in that capital with a traffic tunnel that functions during heavy storms as a stormwater detention reservoir.

Washington Harbour Dual Purpose Parking and Flood Control Garage Rotterdam Dual Purpose Flood Control and Parking Facility Kuala Lumpur Dual Purpose Flood and Traffic Tunnel

Washington Harbour

Illustration of Flooding of Parking GarageArchitect Arthur Cotton Moore FAIA designed the underground parking garage at Washington Harbour in the Georgetown neighborhood of Washington to do double duty as a floodwater retention facility. When the Potomac River floods, flood water is allowed to flow into the garage.

Kuala Lumpur

The SMART Tunnel in Kuala Lumpur addresses some of the same problems and needs as the National Mall Underground. Traffic congestion and flash flooding are two urgent problems solved by the dual-purpose Stormwater Management and Road Tunnel (SMART) in Malaysia’s capital. The roadway, relocated into a three-level tunnel under the downtown area, can be flooded on one, two, or all three levels during flash flood events. The SMART tunnel has saved the city from more than seven major storms since it opened in 2007. SMART is a product of a joint venture between the private section (roadway) and the country’s Highway Authority and Department of Irrigation and Drainage (DID). The system’s projected benefits include the prevention of billions of dollars of possible flood damage as well as billions of dollars in savings from traffic congestion. The SMART tunnel is honored in a series of commemorative stamps, shown below. Visit www.smarttunnel.com.my for more information.

Kuala Lumpur SMART Tunnel Commemorative Stamps


In the Netherlands, the city of Rotterdam is taking what it considers a “holistic” approach to combating the perennial challenges of flooding by developing dual-purpose stormwater collection facilities including neighborhood “water plazas” able to retain storm water and prevent flooding, and green roofs that absorb rain water and prevent runoff. The innovative dual-purpose Rotterdam Museumpark is both a parking garage for the city’s museum district and a stormwater reservoir. The reservoir is capable of storing 10 million liters of stormwater in times of heavy rainfall and 1,150 parking spaces. The structure was designed to blend with the surrounding park area, using atriums, glass stairwells, and steel columns to create a transparent, seamless effect.