I’m a civil designer. I model the roads you drive on, and the water pipes under them - stormwater, wastewater. I size it all up, do all the calculations, then model it to make sure it’ll all fit where it needs to go, then send that to the contractors.
I got into this in my late twenties after spending some time as a professional cyclist. I did a bit of triathlon at high school and road cycling was my strength so I went with that and joined a New Zealand development team based in France.