grading

I know from my site model and from visiting the site that the engineering of the park will be a little trickier than the Woodall-Rogers Freeway park in Dallas. The park in Dallas is flat and straight. The terrain in Nashville, typical to Middle Tennessee, contains rolling hills. There is also the issue of surrounding ramps, which I have expressed concern with before discussing the possibility of these ramps limiting accessibility to and from the park. There must be proper clearance below not only for interstate traffic, but also for vehicles exiting and entering the highway. I am by no means a structural engineer, but do need to have a good understanding of how this would work. I will likely learn more during my next committee meeting (3 architects, 1 landscape architect) but for now, I am using the thickness of a parking garage floor I measured (38”) with the required bridge clearance for an urban interstate (14’…I used 14.5’ for a little extra room). This comes to 17’8”. I rounded up and decided the deck needs 18’ from the surface to the interstate below work.

 My site map only has 4’ contours, so it is not exact. I feel that I now have a good idea of where how the ramps will affect the deck above. Bottom line is that there is less room for these ramps than I had originally thought. The drawing below shows where the deck can occupy space without regarding the ramps. As I begin to conceptualize the master plan, I will decide if the ramps should be regraded or not.

As stated before, the rolling terrain will have to be dealt with. My next step was to draw out how the park would be graded to make the existing grade transitions at the edges of each deck as smooth as possible. The deck grading could be thought of as a base map for the deck. It can be modified of course, but this shows the smoothest transitions possible without changing the elevations at each corner or each of the sections. Certainly, regarding at the edges will probably be desired in some areas. The green represents the deck. Solid lines are at existing grade while dashed lines represent edges that are not at grade. Again, this is partly due to the existing topography and partly due to the ramps at the edges. Pedestrian access can only be gained where the deck is at grade with the existing topography, mostly at the corners for three of the sections.