Don,
There was a recent in-depth article written about these barriers:
Giblin, Kelly. “The Jersey Barrier."
Invention & Technology Volume 22 Summer 2006.
A side note: this is my 'most favorite' magazine ever. Articles are written about things that you may have never had any previous interest. By the time you are finished reading you have indeed gained some amazing knowledge about this now fascinating subject matter. Unfortunately, it only comes out quarterly... After re-reading the article this morning to assist with your question I was unable to see any reference to your original question regarding the 'K-rail'. Here is the on-line link to the article:
http://www.americanheritage.com/articles/magazine/it/2006/1/2006_1_26.shtml