ahhh tracks....as I am not into racing at all, this didnt occur to me. You know the 1976 Olympics were held here, and there was a Velodrome (right beside the Olympic Stadium) but ages ago it was converted into a nature center, called the "Biodome" (is really neat, with a number of "climate zones" that one walks through with real and "set-like" environments with birds, animals, fish. A great place to visit with kids)
Kinda sad that an Olympic level facility was not used enough to warrant the change, but I dont honestly remember the details of when it was taking place.
I imagine the use was not warranting the upkeep etc.

cheers