Modeling Parking Garage Ramps

While I’m a HUGE fan of reducing parking requirements for housing and mixed-use projects, there is still a need to design (and model) parking garages.  This can be a real challenge to new Revit users, as there IS a ramp tool, and it’s supposed to be automatic, Right? Right.  But like many real world situations, the basic ramp tool isn’t much help when it comes to the complex shapes and required slope transitions that constitute parking garage ramps. In fact, I don’t advise using the Ramp tool at all – build them more accurately with Floors!

Checklist summary:

  • Define the area constraints (surrounding walls, start/stop of ramp location)
  • Know your slope and transition (blend) slope guidelines
  • Create floors for each segment of the ramp
  • Add up inside edge length of all floor segments (by slope %)  *tangent of angle = Opposite/Adjacent
  • Modify Points of each floor segment to drop each inner corner (slope must work at the shortest route)
  • Verify ramp endpoints correspond to deck heights (expect slight tweaking)
  • Modify points of each floor segment to drop each outer corner
  • GROUP the overall ramp to minimize accidental editing
Ramp - define slope goals
18% MAX slope midfield
9% (1/2 MAX slope) as ‘blend’ transitions
Level edges at connection to garage levels, level cross slope at straight segments.
Add Inner Lengths
Add up Inner Lengths:

9% slope (9′ + 11′-10″) = 20′-10″
18% slope  = 29′
X% slope @ corners (11′ + 10′-6″) = 21′-6″
 Tangential formula

Calculate 9% slope inner corner elevations from either end.

Top of ramp:  0″, -17″
Bottom of ramp:  0″, +21″
Drop of 18% slope mid section:   -113″
Blend + straight sections:  17″ + 21″ + 113″ = 161″
So we know we have more drop than is needed, and can reduce the slope %.  Reduce slope on curving transitions,  when possible.
Modify SubelementsRecalculate the floor corner drop per the adjusted slope angle.
10% + 5% slopes:  -10″, -33″, -94.5″, -116″, -120″
Select each segment of flat floor and Modify Sub Elements
That gives us the slope at the inside edge. Verify the end elevation, and adjust if necessary. Repeat setting the drop at the outer floor corners:  GROUP and COPY TO ASSIGNED LEVELS (where Deck-to-Deck is equal dimension).
Ramp - two side sloped
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