Which tech gives bridges?

[Nemo]

Ok, I have noticed this for sometime now but haven't pinpointed its origin. When you build a road over a river in the beginning of the game, that square costs 1MP instead of 1/3MP (MP=Movement Point). Howerver, at some point in the game, roads over a river become 1/3MP. What tech/event changes this? i.e. what tech allows for this "bridge building"?

Thanks

 

[Thunderfall]

This is taken from the Civ3 Info Center:

Effects of rivers: Rivers now run along the edges of squares, not through them. The effects of rivers on movement and combat have been changed a bit, as follows:

• No fast movement: Civilization II allowed ground units moving along rivers to travel faster—as if moving on a road. This game offers no movement bonus for river travel.
• Combat bonus: If combat takes place across a river—the units are on different sides when the combat begins—the defender gets a bonus.
• Movement cost: Until you discover Engineering, your units do not enjoy the road bonus to movement when they cross a river.

 

[Nemo]

Thanks! Something I obviously overlooked, sorry

 

[Lt. 'Killer' M.]

Wow, Thundy-Bundy comes down to the lowly marshes of newbie help! Great!!!!

I`ve seen so many places where the mods think they`re GODS that I still marvel at how this place can be sooooo much better!