One way to make this visually clearer to the player, is by highlighting the lines of the contracts you can actually bid on at that moment. Just a slight change in colour along with a text akin to what Frankschtaldt wrote.
"Projects where all requirements needed to be able to make a bid are met, are highlighted in screaming neon pink."
Edit: Just to be sure. Leaving the unavailable projects still listed might work as a good incentive to branch out and expand. When I play I tend to be forgetful (and lazy) so I end up using ages to expand geographically.
"Projects where all requirements needed to be able to make a bid are met, are highlighted in screaming neon pink."
Edit: Just to be sure. Leaving the unavailable projects still listed might work as a good incentive to branch out and expand. When I play I tend to be forgetful (and lazy) so I end up using ages to expand geographically.