The valves would limit intake to prevent causing a shockwave, and be spaced close enough to neutralize any shockwaves caused by catastrophic failure. You could

The valves would limit intake to prevent causing a shockwave, and be spaced close enough to neutralize any shockwaves caused by catastrophic failure. You could even open the valves intelligently, limit the valves as a function of the distance of the failure point. So the valves closest to the failure open the fastest to put air ahead of the shockwave, and the valves further away open slower to give further away carriages more time to break.