In 1994, Rutgers University's Plastics and Composites Group, formerly the Center for Plastics Recycling Research was grant funded by the New Jersey Commission on Science and Technol-ogy to develop and test composite railroad ties made from recycled plastic. Since the inception of this project, the major participants have been Rutgers University, Earth Care Products, Inc. (US Plastic Lumber), Conrail, Norfolk Southern, and the US Army Corps of Engineers.
The base mixture of materials targeted for use in this application is predominantly high-density polyethylene from milk bottles, detergent bottles, and the like. Much of the 3.27 Kg (7 .2 billion pounds) of this material that is generated anually in the United States is land filled1. Govern-ment regulatory agencies recognize that land filling as the least favorable disposal strategy, and that the possibility exists that in the future there may be economic incentives for products con-structed from recycled plastic.
Alternatives for the wooden crosstie are being considered because of the desire to increase tie service life and also due to changing economic and regulatory conditions, which may impact the railroad industry's ability to use creosoted wood in the future. Particularly in moist, humid sur-roundings, the activity of biological organisms limit tie life. Plastic crossties are not subject to the attack of these organisms. Other traditional modes of failure include "spike killing" and tie plate cutting. Both are due to the accumulated effect of heavy axle loads, as measured in MGT (millions of gross tons). Economically, as the hardwood market continues to become more global in nature, wood will be diverted to uses more profitable than crosstie manufacture. Also, it is apparent that over the past twenty-five years environmental regulations have become more stringent. It is in the railroad industry's interest to research crosstie materials that do not require a preservative. The research into plastic/composite crossties is timely because of the lag time required to prove engineering design criteria and economic benefits in revenue service.