How to depict a common bridge that carries several roads and links?

Hi

In Bangalore (India), we have a underpass at a location called Marathahalli, in which-

1. The East-West 4-lane Varthur road passes on the upper deck (a massive RCC structure)
2. The North-South 4-lane Outer Ring Road ("ORR") passes below this deck.
3. The ORR and Varthur Road are joined through 4 loops (called "service roads"). These service roads climb up to the upper deck's level through ramps.
4. The upper deck also carries two links that provide a U-turn for the ORR
5. Pedestrians use the remaining space on the upper deck to cross between the two major roads.
6. The upper deck also has small traffic islands that separate the above features.

At present, the RCC deck is not shown properly:

1. Both halves of the Varthur road are shown as if they pass over two separate bridges.
2. The links are shown "hanging" (not shown as situated on the upper deck).
3. The pedestrian area on the upper deck is not shown at all.

I would like to know how to depict this construction correctly. Please help!