Build a tunnel from one end of the map to the other and the tunnel will be so expensive that the price will get a negative amount that will be added to your account.

Hint To ruin a good road network for a competitor, simply place a rail piece at right angles over a piece of road, then use the bulldozer to destroy it. The computer will not rebuild it!

Transport Tycoon Deluxe
Make Millions of Dollars the dishonest way!
Step 1: When a company is about to go bankrupt and asks you if you would like to purchase the company, say "No".
Step 2: Open up that company's window and purchase 75% of their stock. DO NOT CLOSE THAT WINDOW!
Step 3: Move the window off to the side of the screen and forget about it for 3 months of game time. The computer player will be declared bankrupt, but the displayed value of the company in the STILL OPEN company window will be in the millions!
Step 4: Sell the 75% of the company you own and you'll make a bundle!

Warning!!! This has crashed my system on several occasions!
SAVE YOUR GAME BEFORE THE THREE MONTH MARK IS UP!!!