May 17 was a day of odd contrasts. At Cornelia’s beautiful old railroad station, three train enthusiasts were standing next to the track with top-quality cameras, waiting to take photos of the approaching northbound Norfolk Southern. The familiar mustang logo on the lead engine rolled by, followed by additional locomotives and a very long chain of flatbed cars carrying containers.

At the same time that I was enjoying a chat with the hi-tech train watchers, two commuter trains collided in Bridgeport, Conn., injuring 63 people. It was a reminder that railroads are efficient and generally safe. But like all other means of transportation, they can’t be made completely fail-proof.

Statistics listed by the Department of Transportation (www.phmsa.dot.gov) are difficult to interpret because the 931 railroad fatalities in a four-year study period included deaths at crossings, which should really fall in the “motor vehicles” category. That one was the least safe, with 36,676 killed in four years. Air carriers fared best, with 138 accidental deaths.

Looking at the environmental impact of transportation, trains and airplanes are about tied for being most earth-friendly in terms of their CO2 footprint. But producing reliable figures about total emissions is very difficult, because commercial planes are powered by gasoline. Trains can be diesel-powered or electric, or hybrids of both.

There are additional factors often neglected in “total emissions” studies. In addition to what comes out of the tailpipe, there’s the impact of building construction. Train stations, freight terminals, airports, as well as the electricity needed to operate them are extremely complex factors. Some electricity is produced from coal, the dirtiest energy around. Some from wind, the cleanest. But it all runs through the same wires, and an electric train may be using both kinds.

What emerges from the vast amount of information is that for safety and lowest impact on the environment, railroads beat road transportation on intermediate distance travel. This is true for light rail as well as intercity train systems, compared to cars and trucks. For distances measured in the thousands of miles, air carriers are doing the cleanest and safest job.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.