Radiation, nuclear warning and bridges?

[Glenn Saunders]

1. Can a bridge, built by an engineer, cross a water hex? or is it only pontoon bridges?

A bridge built by Eng over a FULL WATER hex is a PONTOON BRIDGE

2. are there any difference between moving over a pontoon bridge (built by an engineer) and an ordinary bridge (built by an engineer), such as movement cost?

A Pontoon Bridge - built by an Eng occupies a hex and for a unit to move in that hex it must pay the MP cost for the hex as defined in the PDT

An ordinary bridge built by an Eng crosses a hexside and units must pay the cost additonal cost in MPs to cross that hexside.

or is the only difference that a pontoon bridge can be built over a water hex.

Correct