Volume Ten - Pre-Victorian to the Present Day - Even more aspects - Investigation into the Condition of the Ely River Subway 1991 . . .

Ring Nos.	Description of Condition	Comments	Photos
401-450	Corrosion of tunnel lining now evidenced by black staining throughout rather than orange.	Sump and lowest part of Subway at Ring 412. Pump for emptying drainage sump still in place.	3/15
451-500	Areas and extent of lamination of cast iron surface appear to be reduced. Evidence of paint system noted once more.	Condition of ring segments generally starting to improve again.	3/16
501-550	Areas of lamination of cast iron surface noticeably reduced when compared to the lining on the other side of the sump. Approximately 50% of total surface laminated to a maximum thickness of 2mm.	Horizontal radius commences at Ring 550.	3/17 3/18 3/19
551-600	No significant change in condition noted. Evidence of air pocket above the flooded level in the Subway crown where paint is still intact.	Flange thickness of segments reverts to 29mm at Ring 596.	3/20 3/21
601-650	Lamination of cast iron surface generally limited to lower and middle segments. Orange corrosion staining noted at end of Subway indicating possible air pocket.	Covers to 11kV cable duct displaced. Water flowing in ducting.	3/22
651-670	Last complete ring recorded at 669; Ring 670 incomplete.	Backfill material at abandoned end of Subway consists of day silt and laying at approx. 20 degrees up to Ring 656.	3/23