Grand Central's Respect for History Is From The Ground Up
At Grand Central Terminal, as in any beloved, well-used old house, renovation and restoration work is continuous.
Take the floor. More than 45,000 square feet of Tennessee pink marble, and even more terrazzo, 67,000 square feet, have withstood the scuffling of millions of feet for 96 years. But everything in this world has its breaking point, and some marble floor tiles and some sections of terrazzo have broken and cracked.
So MTA Metro-North Railroad, the steward of the Terminal, has embarked on a five-year program to replace broken tiles with newly quarried ones and to pour new terrazzo. About 25% of the floor needed replacement. Now in the third year of the program, we are repairing about 5% a year to minimize disruption to the 700,000 pedestrians who pass through the Terminal each day.
The very process of chiseling out the broken floor sections and then setting in new ones is difficult enough, but the hardest task is the acquisition, selection, and emplacement of the marble and terrazzo so that it is indistinguishable from the original, adjacent sections.
To acquire an exact match of the Tennessee pink marble, we went to the quarry from which the original stone was cut. It had been closed since the late 1980s, but the owners agreed to reopen it in order that Grand Central Terminal could attain identical marble as the original.
The original slabs of marble were placed just 1/16th of an inch apart. This tight fit, however, left little room for "give" when the building vibrates as it does when trains travel around its loop tracks.
The replacement slabs are placed with double the space between them. The 1/8th inch separation that is now the standard is invisible to the casual eye and will prevent cracking.
The original terrazzo-which is an aggregate of crushed stone and cement-is of a unique color and make-up for which there is no modern equivalent. The original "mixture recipe" was lost to history.
So a laborious and exacting process of trial and error ensued with multiple mixtures, combinations, and processes until-finally-a perfect color match was achieved. The recipe for this perfect mixture was written down and is kept in a secure, locked drawer within Grand Central.
The terrazzo work takes about a week because it requires multiple processes. First the old stone is chopped out. Then the new stone mixture is poured. It requires several days to "set" depending on the humidity. Then grinders produce a smooth, level surface and finally it is polished to perfection.
The terrazzo slabs, which are actually "softer" and more prone to wear and cracking than the Tennessee pink marble, now have an almost imperceptible brass border on all sides. This modern addition stops any cracks that have developed in one slab, from transferring to the next slab-and then the next.
This floor rehabilitation project began in mid-2007 and will be finished in 2012.
You can try looking for the new and shiny sections of GCT's floor, but you won't find them, thanks to the meticulous work of master stone masons.