This challenge is still open :-) and allows a short small game.
Pak64. No Addons. Played on a random small map without tourist attractions, a few cities. At game start roads were already built but I have not used them.
As required I built 2 Passenger routes and 4 cargo routes - using only Electric Trains. No other vehicles.
Here are the two passenger lines. There is one train on each route.

Passenger1: A loop calling at 11 locations (Marked 1 to 11). It does not stop at cities B+C forcing passengers to change to high speed at '1+A'
Passenger2: is a High Speed line connecting the three biggest Cities.(Marked A to C)
The high speed train waits for a 70% load at station '1+A' which usually means it waits for the other train to arrive at station 1. Passengers then transfer to the high speed train and both trains set off together on their separate tracks. The slower train on the loop is a BR185 with faster acceleration. Despite starting a fraction later and turning a curve soon overtakes the higher speed Class86. The Class86 has a higher top speed so will regain the lead later.
I had tried a faster train on the high speed line but it was not profitable. I changed the train and coaches. These slower passenger carriages take more passengers and have a lower maintenance cost. I used a slower/lower cost locomotive as the coach sets the speed limit for the high speed service (160km). It only took a few trips to turn the loss making high speed route into the now successful route required by the challenge objective.