Canadian National Railroad Practice Exam

In a large urban area, trains must operate under tighter safety constraints where track infrastructure, signals, and street traffic create more potential interactions. HTUA stands for High-Traffic Urban Area, where the pace of operations is balanced with the need for quick stopping and precise control around crossings and busy yards. Because of these factors, a lower speed is set to reduce braking distances and reaction time requirements, enhancing safety while still allowing reasonable movement through dense zones. That’s why the maximum through-HTUA speed is 35 mph. Higher speeds like 45 mph or 55 mph are typical outside HTUA in less congested mainline sections, while 25 mph would be reserved for highly restricted areas such as yards or terminal approaches. So, the maximum speed through HTUA in a large urban area is 35 mph.