The technologies in question are Two-Man Saw, Gold Shaft Mining, Stone Shaft Mining and Crop Rotation.
Why? All these technologies are rarely used because their benefits doesn’t outweigh their cost or ther benefits take too long to be useful or it is better to invest in army than to invest in these technologies.
Solution that i propose to make these technologies more interesting and useful in the long run, not as long as just the speed bonus would take (perhaps in a team game)
Gold Shaft Mining and Stone Shaft Mining not only guarantee the speed bonus but make the resources last longer by 15%**, like Mayan civilization bonus.
Two-Man Saw makes the resource last 10%** longer
Crop Rotation increases FARM speed by 0.2 f/s**
Given that not all civs have these technology, i suggest to give them, perhaps with another name, but with similar effects modified for balance.
**Numbers need to be balanced depending on civs.