Sometimes the best way to learn is by making mistakes. The construction of the Erie Canal was riddled with learning through mistakes. As Professor Jones states in his lecture on the Erie Canal, trial and error was common in early American engineering. (Jones Lecture, “Unit 2: French and British Influence,” 1:56) Almost no Americans had formal training in Engineering and no experience in building Canals. They learned as they went along the job, and this had many strengths and weaknesses, but ultimately they were successful in the construction and learned what worked and what did not work. And because those lessons were learned the ‘hard way’ the lesson stuck. Because of this, I would say, the Erie Canal was a success “first school” of engineering.
One of the best strengths in learning on the job was it enabled the builders to research multiple successful foreign techniques and figure out how to put them together to make it work. This form of taking the aspects of those techniques that worked and getting rid of those that did not, and working through a problem rather than having the answers given forced the construction workers into becoming engineers.
The weakness of such a ‘school’ is that errors are costly. And when learns through making mistakes it can waste time and money, and can be unsafe. Also, many important lessons can be missed or incorrectly learned. For example an instrument could be used incorrectly, like a level, and if that is the way an engineer learned to use it (even if it worked for the Erie Canal) that might cause problems on a different job.

In response to the idea of a modern John Jervis being successful in today’s world, simply put, I do not think it is possible. That is not to say that a person cannot learn how to be an engineer without formal college training, but in today’s world without that piece of paper stating he