never use train’s in a city.
at early year’s you only need to connect the brightest spots in one city. e.g. try one station in the bright green, one in the bright red and one in the bright blue zone. then connect those stations. you do not need to make a loop. after that you can do a station at you train station and then connect one city with another with the railroad and in that city you can image that build. also you need to keep the frequency low (at around 100sec at early game).