A few years ago, when I was in my second year of civil engineering, our department organised a field trip to the Tarbela Dam in the north of Pakistan. It's one of the largest earth-filled dams in the world, built across the Indus River, and for engineering students it's almost like a pilgrimage.
We travelled up by coach from Lahore, which took most of the day, and stayed one night in a hostel nearby. The next morning an engineer from the water authority showed us around.
The first thing I noticed was the sheer scale of it. The reservoir behind the dam stretches back further than you can see, a huge body of grey-blue water surrounded by dry hills. We walked along part of the top of the dam, saw the spillways where excess water is released, and then went down into the power house, where enormous turbines were humming away. It was so loud we had to shout.
What I learned was much more than the technical details. Of course, we had studied how dams work in lectures, but seeing it made me understand how much one structure affects millions of people. The engineer explained that the dam supplies water for farming across a large part of the country and also produces a big share of our electricity. But he was also honest about the costs. Thousands of families were moved from their villages when the valley was flooded, and silt is slowly filling up the reservoir. That balance between benefits and sacrifices really stayed with me, and it's something I now think about whenever I work on any project.