Air Carrier Captain reports receiving a nonstandard taxi clearance and the First Officer reading it back incorrectly. The crew nearly taxis onto a closed portion of Taxiway Y at DTW.

Narrative

Enroute to Runway 22R crew received; from ATC; instructions to 'taxi to 22R via U; Y; K4; K'. This was a 'non-standard' routing. This was a 'threat'. First Officer read back 'U; Y; to 22R'. This was an error. Captain and Jumpseat pilot failed to catch this mistake. This was an error. ATC failed to pick up on the incomplete 'readback'. This was an error. Crew was busy (distracted) with pre-departure tasks. This was an error. As the aircraft approached the south edge of Y-K4 intersection.... The First Officer announced 'STOP'! This was the action that 'broke the chain of errors'. (The taxiway was blocked off with construction barriers.) The Captain quickly brought the aircraft to a complete stop. Sufficient space was available to make a left turn and proceed with the taxi. The rest of the flight was uneventful. Valuable lessons were (re)learned.Preventive Measures:1. Carefully screen pre-departure NOTAMS. (Often very difficult with several pages of detailed construction related NOTAMS.) 2. Carefully listen to and read back ATC instructions. 3. Encourage ATC to listen and respond to incomplete read backs. 4. Encourage Airport Operations to mark closed taxiways with more conspicuous lighting. 5. Captains need to prioritize the many tasks required during taxi and delegate the critical tasks. eg.'...you taxi; I'm heads down.'