Not heavy rail...just "heavier" rail. They are both trolley operated systems. Here is the definition of "heavy rail":


"Heavyrail may be defined as a type of urban passengertransportation servicethat utilizes electrically propelled trains of cars operating over fully grade-separated rights-of-way. Heavy rail may best be envisioned as high-capacity, semiautomated trains of four to 10 cars powered by electricity from a third rail. Because heavy rail systems require an exclusive, completely grade-separated alignment, extensive subways and elevated structures are needed, both of which are costly and disruptive to construct. Fare collection is typically done at stations, and boarding is from highlevel platforms."

http://www.trainweb.org/kenrail/Rail_mode_defined.html