Railroad Crossing Bridge

I'm Michael (please don't leak) I'm 14 and am currently in 8th grade. I wanted to design this bridge to easily get to another section of my city by passing above the train tracks and saving about 7-8 minutes of cycling.

Now knowing how long and how high the bridge should be, we should now start making the bridge.

Start by making a a long rectangle. I made mine around 3meters thick (1mm=10cm) Then, add 2 walls on the sides. make sure that they aren't too thick. After making the walls, add some rectangle holes in the side walls by adding a small rectangular hole, then select that hole, do ctrl d, then move that hole a bit to the side, then press ctrl de continuously. Finishing the holes, select all and merge all. Now, you are done! Use your creativity to make whatever bridge you want!