The Life of a Subway Car: From Mass Transit to Aquatic Habitat

diveblog1Do you ride a subway to work? Do you know anyone who lives in a city where subways or other rail mass transit systems are used? Subway and rail mass-transit systems are a very efficient and economical way to travel in a city.  Some of the largest mass transit systems in the U.S. are in the Mid-Atlantic and New England Regions of the EPA:  Southeastern Pennsylvania Transportation Authority (SEPTA), Washington Metropolitan Area Transportation Authority (WMATA), and Metropolitan Transportation Authority (MTA).  Each of these transportation agencies utilizes dozens of subway and regional rail cars, replacing their fleets as they age.

As cars are removed from service, you may wonder: “What happens to the rail cars after they’re decommissioned?” The answer is that some go to scrap yards to be dismantled and re-sold to manufacture other metal structures.  Others, such as the Red Bird fleet of New York’s MTA, have been used to form artificial reefs.  Several of MTA’s Red Bird decommissioned cars were sunk off Delaware’s coast, approximately 16 miles from the mouth of the Delaware Bay, to serve as an artificial reef.  This reef was first examined by EPA’s Dive Team in June 2009 as part of an ongoing effort to determine its benefits and status.  Artificial reefs can be colonized by organisms like corals and sponges and provide nursery habitat for wide range of finfish and shellfish, which can increase regional aquatic biodiversity and coastal tourism through fishing.

With these benefits in mind, the question remains: What man-made structures create the best artificial reef habitat?  In addition to subway cars, decommissioned boats and ships have been used as reef structures.  EPA is currently determining whether subway cars remain intact as solid, sustainable structures for aquatic life.  Specifically, we’re examining whether there’s a difference in the structural integrity and aquatic life use between carbon steel cars and stainless steel ones.

diveblog2EPA completed its second survey of Delaware’s Red Bird reef site on June 2 – 9.   I was one of fifteen EPA scientist/divers who surveyed the condition and function of the subway car artificial reef.  This was my first dive survey since joining EPA’s Dive Team in May of 2010, and it was an exciting experience.  At first glance you may think that such dives are easy – after all, how difficult could it be to dive and look at a bunch of subway cars?  The reality is that these cars were sunk in 85-95 feet of water, the temperature at the bottom is 48º F, and the visibility was only about 10 feet in any direction.  This means that first we had to locate individual cars from the surface and dive to them. Once anchored to the car, we used a wreck reel and swam in each direction to find other cars, all without losing track of the anchor line.  Having been through EPA Diver Training, I found that swimming in such an environment wasn’t too difficult, but it definitely took some getting used to. Throughout the week-long survey, the team collected information on the structural condition of the cars, percent cover of encrusting organisms, and height of aquatic growth on the cars at six specific reef locations.  The team utilized video and still photos to document findings.

The data we collected will build off of initial information EPA gathered during the first visit to the sites in June of 2009.  This data will be analyzed by EPA and its partner agencies and will ultimately contribute scientific data to the question of whether more artificial reefs, using subway cars and other clean, steel structures should be created. Click for more information about the concept of artificial reefs, and about EPA’s Dive Team.

Also check out this post about other research being done on the OSV Bold on the newest EPA blog – Region 2’s “Greening the Apple.”  We’re excited to welcome them to the EPA blogosphere!

Editor's Note: The views expressed here are intended to explain EPA policy. They do not change anyone's rights or obligations. You may share this post. However, please do not change the title or the content, or remove EPA’s identity as the author. If you do make substantive changes, please do not attribute the edited title or content to EPA or the author.

EPA's official web site is Some links on this page may redirect users from the EPA website to specific content on a non-EPA, third-party site. In doing so, EPA is directing you only to the specific content referenced at the time of publication, not to any other content that may appear on the same webpage or elsewhere on the third-party site, or be added at a later date.

EPA is providing this link for informational purposes only. EPA cannot attest to the accuracy of non-EPA information provided by any third-party sites or any other linked site. EPA does not endorse any non-government websites, companies, internet applications or any policies or information expressed therein.