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

Results of Survey

Summary of Findings :

The remains of the Subway were found to be generally in good condition considering the history of the Subway since closure.

Deterioration of the cast iron lining was slight.

Water ingress between segments, as evidenced by stalactites, was slight. It had been possible to pump the Subway dry for the purpose of the survey, and the main source of water ingress during the survey was through the partly demolished southern end which had not been properly sealed but simply backfilled.

Detailed Report of Findings :

For the purpose of the survey, the tunnel lining rings were consecutively numbered, starting with Ring 1 at the northern portal and finishing with Ring 670, the last remaining ring at the southern end.

Initially it had been intended to report on each ring; in practice the condition from ring to ring was found not to vary considerably and it was therefore decided to comment on batches of 50 rings for which an appraisal is given in Table 1 at the end of this section. The ring numbering system adopted against chainage is indicated on drawing 1542/02.

Water Ingress into the Subway :

No significant water ingress through the tunnel lining was observed, though a steady dripping from a number of stalactites was noted. Of the 670 rings that remain, stalactites were noted at 61 of the joints between the rings. The stalactites identified during the survey did not appear to be a source of significant water ingress. The prime cause of water ingress during the survey was caused by seepage through the backfill material at the demolished end of the Subway.