+----+  +-------+                                    +-------+  +----+
| R1 |  |  R10  |                                    |  R30  |  | R4 |
| L2 +--+ L1/L2 +--------------+   +-----------------+ L1/L2 +--+ L2 |
|    |  |       |  L2 adj      |   |      L2 adj     |       |  |    |
+----+  +-------+  over        |   |      over       +-------+  +----+
                   tunnel      |   |      tunnel
+----+  +-------+           +--+---+--+              +-------+  +----+
| R2 |  |  R11  |           |   R21   |              |  R31  |  | R5 |
| L2 +--+ L1/L2 +-----------+  L1/L2  +--------------+ L1/L2 +--+ L2 |
|    |  |       |  L2 adj   |  flood  |   L2 adj     |       |  |    |
+----+  +-------+  over     |reflector|   over       +-------+  +----+
                   tunnel   +--+---+--+   tunnel
+----+  +-------+              |   |                 +-------+  +----+
| R3 |  |  R12  +--------------+   +-----------------+  R32  |  | R6 |
| L2 +--+ L1/L2 |  L2 adj                 L2 adj     | L1/L2 +--+ L2 |
|    |  |       |  over                   over       |       |  |    |
+----+  +-------+  tunnel                 tunnel     +-------+  +----+