During both World Wars he prepared military traffic control codes that were used overseas.  He designed the rotary traffic plan used in New York and several foreign cities.  Perhaps his chief claim to fame is the endowment and the incorporation of the Eno Foundation for Highway Traffic Control in 1901 which for many years carried the brunt of foundation activities in highway traffic.  

In his lifetime he received a B.S. and an honorary M.A. degree from Yale University and was decorated twice by the French Government.  He was a fellow of the New York Academy of Sciences and the author of eight books on traffic translated into four languages.