Fix support columns: cylinder axis transposition + floating ramp piers

Two structural bugs found by measuring built parts, not by eye.

1. PierColumn (pre-existing, all 80 instances). Enum.PartType.Cylinder
   puts the circular faces on the local X axis, so Size.X is the length
   ALONG the axis and Size.Y/Z are the diameter. The code passed
   Size = (8, colH, 8) and then rotated 90deg about Z -- building a disc
   8 studs long and colH wide. Measured: world vertical extent 8.0 studs
   for a column that should stand 35.4, leaving every viaduct pier
   floating with a 13.7-stud gap down to the ground. Only the Size
   components were transposed; the rotation was already right.
   After: extent 35.4, base Y=0.0.

2. PARampPillar. Two problems.
   a) Built as 6x6 square blocks. The underside footage (honmoku_jct
      sheet3 -- mislabeled, it is actually shot beneath Daikoku itself)
      shows every column carrying the ramp decks is a smooth cylindrical
      concrete pier. Now Cylinder, same axis convention as PierColumn.
   b) Height was always segMid.Y - (ringY - 1), cutting the column off
      at Y=45, the underside of the PA apron slab. Correct only while
      the ramp is over the slab; the measured helix climbs up to 1182
      studs beyond the slab edge, where nothing exists at Y=45. Base is
      now chosen per-pillar: apron level over the slab, ground (Y=-1)
      beyond it, matching the established viaduct Pillar convention.
      After: all bases at Y=-1, 0 pancakes, min height/width ratio 1.7.

Ramp geometry, chevron alignment and gore zebra all unchanged:
0 misaligned panels (worst 0.06/0.08 studs), 832 gore bars, merge
mouths 24.0/23.8 studs from the nearest bar.

src/server/MapBuilder.luau

@@ -654,16 +654,28 @@ local function buildRoad(map: Folder)
 						Material = Enum.Material.Concrete,
 					})
 					cap.Parent = struct
+					local colH = capY - 1.6
 					local col = part({
 						Name = "PierColumn",
-						Size = Vector3.new(8, capY - 1.6, 8),
+						-- Enum.PartType.Cylinder puts the circular faces on the
-						CFrame = CFrame.new(mid.X, (capY - 1.6) / 2, mid.Z),
+						-- LOCAL X axis: Size.X is the length ALONG the axis and
+						-- Size.Y/Z are the diameter.
+						--
+						-- BUG (found 2026-08-03 by measuring the built parts):
+						-- this passed Size = (8, colH, 8), i.e. 8 studs along the
+						-- axis by colH wide -- a disc, not a column. Measured on
+						-- all 80 instances: world vertical extent 8.0 studs for a
+						-- column that should stand 35.4, leaving each pier
+						-- floating with a 13.7-stud gap down to the ground.
+						-- The Z rotation below was already correct; only the Size
+						-- components were transposed.
+						Size = Vector3.new(colH, 8, 8),
 						Color = C_CONCRETE,
 						Material = Enum.Material.Concrete,
 						Shape = Enum.PartType.Cylinder,
 					})
 					-- Cylinder's axis is X, so stand it upright.
-					col.CFrame = CFrame.new(mid.X, (capY - 1.6) / 2, mid.Z) * CFrame.Angles(0, 0, math.rad(90))
+					col.CFrame = CFrame.new(mid.X, colH / 2, mid.Z) * CFrame.Angles(0, 0, math.rad(90))
 					col.Parent = struct
 				end
 			-- Elevated viaduct: support pillars down to street level
@@ -1469,14 +1481,34 @@ local function buildPA(map: Folder)
 
 			-- Support pillar down to the apron under the raised part of the
 			-- ramp, matching the reference photos' elevated structure.
-			local h = segMid.Y - (ringY - 1)
+			--
+			-- Round, not square (corrected 2026-08-03 against the underside
+			-- footage in honmoku_jct_sheet3, which is actually shot beneath
+			-- Daikoku itself): every column carrying the ramp decks there is
+			-- a smooth cylindrical concrete pier. These were 6x6 boxes.
+			--
+			-- The base has to be chosen per-pillar. The old code always cut
+			-- the column off at `ringY - 1` (Y=45, the underside of the PA
+			-- apron slab). That is right only while the ramp is still over
+			-- the slab. The measured helix climbs up to 1182 studs BEYOND
+			-- the slab edge, and out there nothing exists at Y=45 -- no
+			-- terrain, no baseplate -- so all 55 columns ended in mid-air.
+			-- Beyond the slab, run them to ground like the viaduct piers do.
+			local overApron = math.abs(segMid.X - c.X) <= APRON and math.abs(segMid.Z - c.Z) <= APRON
+			local baseY = overApron and (ringY - 1) or -1
+			local h = segMid.Y - baseY
 			if h > 10 and s % 2 == 0 then
 				local pil = part({
 					Name = "PARampPillar",
-					Size = Vector3.new(6, h, 6),
+					-- Cylinder axis is local X, so Size.X is the height and
-					CFrame = CFrame.new(segMid.X, segMid.Y - h / 2, segMid.Z),
+					-- Size.Y/Z the diameter; the Z rotation stands it upright.
+					-- (Same transposition that had all 80 viaduct PierColumns
+					-- built as 8-stud discs -- see the PierColumn note above.)
+					Size = Vector3.new(h, 6, 6),
+					CFrame = CFrame.new(segMid.X, segMid.Y - h / 2, segMid.Z) * CFrame.Angles(0, 0, math.rad(90)),
 					Color = C_CONCRETE,
 					Material = Enum.Material.Concrete,
+					Shape = Enum.PartType.Cylinder,
 				})
 				pil.Parent = pa
 			end