There are a couple of short term parking spots a few yards South of the cache, on Joseph C Wilson Blvd that are most of the time available. If you plan on staying around a bit longer, you may look for another parking spot in one of the streets around (Gregory, Sanford or Cypress St.).
Look first for a historic marker.
From there, you will find the geoacache following the steps down below:
1. the direction to go is given by puting together some of the letters you can find on the plate: the 3rd, the 1st and the 3rd letter again. Look at your compass carefully, do not approximate.
2. the distance to go is given by substracting "the additional width of the bridge" from "the age of the bridge at the time of its rehabilitation" (this distance is given in decimeters).
3. the rehabilitation date gives you the height of the geocache from the floor (in millimeters this time).