Pros
Nice people, not many jerks, most of them pretty smart, get to work on major transportation projects, pays pretty well, offices are pretty nice.
Cons
A new CEO took over in 2017, and he had a much more aggressive agenda than the previous one, which led to problems. They had been doing amazingly well already leading up to that, so he decided to take it up a notch with ridiculously aggressive growth goals. In order to meet the new goals, they focused their efforts mostly on winning huge projects, without balancing the portfolio out with medium and "small" projects (small is relative for HDR). This led to a huge rollercoaster in workload that even spreading work among other offices couldn't help. At one point, there were huge deadlines for three huge projects all at once, so people were working ridiculous hours to meet them, followed by months of not having enough work. People were taking their vacations just to avoid layoffs during the slow period before the next peak. Summers became burnout-busy, and winters became scary-slow.