Commercial Fixed Wing
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Situational Awareness; Troubleshooting; Communication Breakdown
ATC Issue All Types; Conflict Ground Conflict; Critical; Deviation / Discrepancy - Procedural Clearance; Ground Incursion Runway
Air Traffic Control Issued Advisory / Alert; Flight Crew Became Reoriented
Environment - Non Weather Related; Chart Or Publication; Human Factors; Procedure; Airport
ATC direct failure to advise hold short of Runway 9C in the initial clearance. After the switch from Ground to another Tower frequency no instruction was given to hold short 9C. We were given clearance to taxi M1; M; right onto Runway 22R hold short of E. Aircraft Y was ahead of us given the same clearance hold short E monitor Tower 132.70. The Aircraft Y encroached Runway 9C as Aircraft Z was on its takeoff roll on 9C. ATC Controller yelled Aircraft Y stop! Immediately after Aircraft Z cancel takeoff clearance STOP! The Aircraft Z appeared from behind the hangars with the nose wheel off the ground in a slight right bank as the Controller said 'Do you see that plane'?  Aircraft Y was given a number to contact the Tower. There are no 'wig wags' installed at any intersections along this runway. There are no stop bars installed. There are multiple obstructions to visibility. Taxiing into the sun is a factor. Runway markings and signage is unacceptable for the size and scope of the runway; and it's intended use. New construction all around the airport with pilots returning to work from furlough; and layoffs or leave of absence. Trust bias that ATC is correct in the instructions given. Attempting to move aircraft with expedience rather than a structured taxi route. No designation of any 'hot spots ' on aeronautical charts. Cease and desist using Runway 22R as a taxiway! The use of this Runway as a taxiway is the inevitable set up for a mass casualty accident!
Air carrier Captain reported observing a critical ground conflict at ORD airport when Runway 22R was being used as a taxiway.