We have succeeded this by doing the following:
First, we needed some solid income. So we built a coal network.
After that, the main lines for the global network were constructed. We wanted to use only one factory, one city, one refinery, one steelfactory and one sawmill:
Slowly the network expands (1999):
40 years later, we connected almost everything (except cities), still not generating enough money for the 1.000.000.000 Euros.
30 years from that, 2067, the network is getting overloaded. Goods couldn't be transported fast enough, which was a huge impact on the profit:
We started to construct a separate line for the goods produced by the factory. We increased the number of lines to the factory from 4 to 8. But it still didn't solve all the traffic jams we were facing in 2086.
Only after we put the goods on seperate lines, the trafficjams we solved:
Then we let the game run for a year and see, we've done it! €1.000.000.000 profit a year! The screenshot also shows the most complex junction in the game (partially)