Dear Sir

I noted with interest that the article on

the modernisation of the Holmesdale Tunnel on the M25 (T&TI May p30) put the risk of a major fire in this 650m long road tunnel at once in 32 years.

This seems a low and precise figure and it would be of great interest to have more information on how it was derived and particularly on the statistics on which it was based.

Yours faithfully

Myles O’Reilly
Chair, BTS Editorial Advisory Board