We think you will find this cache a bit tricky to locate. First of all, it is difficult to obtain a signal lock, because there are about 7 bridges over your head blocking out signals. Secondly, there really isn't anywhere to look. It isn't a teeny micro either. It isn't super large, but we stocked it initially with three travel bugs and quite a few trade items, so it isn't some film can either.
It is in a fairly exposed spot, so do what you can to avoid getting it stolen. You will probably find it easiest to search on weekend daytimes in terms of avoiding large numbers of bystanders.
The famous Triple Crossing is located nearby. We've never seen trains on all three levels, but we've seen them on the two higher ones several times. At one point, these three tracks were owned by three different railroads and Richmond was a critical central point for traffic from far and wide. 
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You should also check out the nearby flood wall with the signs indicating the highest floods ever seen in the area. There are also some excellent exhibits a bit closer to the Mayo bridge commerating some more of Richmond's boundless history. The Mayo Bridge, by the way, was the first bridge built to cross the James, back in 1787. Make sure you check out the famous box and think about what that must have been like.