Caption: Construction of CN's new St Clair tunnel was preceded by a ceremony featuring the new white-painted Tunnel Boring Machine (TBM) "Excalibore" at the Sarnia portal of the tunnel on 16 September 1993.
The TBM broke through in Port Huron MI on 8 December 1994, about 8 months behind schedule. Much work remained; the first train though the new tunnel was on 5 April 1995.

Shortly after the break-through, the TBM was removed, dissassembled, loaded onto railcars and returned to Sarnia on the car ferry, en route back to the Toronto area.
In this picture, components of the TBM are eastbound on the Dundas Sub near Colborne St in London Ontario, on a dimensional train powered by SD40u CN 6002. Weather was marginal for photography and deteriorating. There isn't much paint left on Excalibore; it emerged from the bore with shiny bare metal, but now rust is showing.
I don't have the date of this movement, my guess is mid to late December 1994. Other frames from the film show the photographer met up with the train again in Stratford - unfortunately he experienced heavy rain/snow there.

From other pictures I have been able to make out the train's 6 freight and 2 passenger cars:
CN 667005 Flatcar - central auger of the TBM
CN 667086 Flatcar - TBM part (spoil conveyor?)
CN 667413 Flatcar - TBM front cutter, disassembled into 2 pieces
CN 670002 4-truck special "well" car - Large diameter internal TBM part
QTTX 30578 Depress Centre Flatcar - half of the TBM outer body
QTTX 30600 4-truck Depress Centre Flatcar - other half of TBM outer body
CN 54954 6-axle Sleeper
CN 70742 "Spirit of the North" converted ex-Baggage car, few windows