Your browser is no longer supported

For the best possible experience using our website we recommend you upgrade to a newer version or another browser.

Your browser appears to have cookies disabled. For the best experience of this website, please enable cookies in your browser

We'll assume we have your consent to use cookies, for example so you won't need to log in each time you visit our site.
Learn more

Eyes glaze over

LETTERS

I love the idea of glazing the whole of the St Pancras station roof (CTRL supplement NCE 28 June). We were not able to take such bold steps when the station was last refurbished some 20 years ago and it will be an improvement on the dark shed we have now.

But I trust engineers and architects understand that the roof structure is a tied arch using the floor as the tie. The picture shows a large number of significant longitudinal openings in the floor which will sever these ties.

The text also suggests that the whole of the undercroft area will be opened out to form a ticket hall and other facilities.

This will remove the support to the floor!

The present floor is, as your article correctly says, a suspended structure supported at close centres on columns. It is a grid of riveted girders supporting buckle plates designed to create a very stiff construction to support the railway tracks. These were converted to the present concrete slab form around 1979 to spread loads and reduce maintenance.

I imagine it will be quite easy to contain the sidethrust of the roof arches into the new concrete box if this extends for the whole area under the station roof. But the first of the openings for the new escalators has been started within the blue painted hoardings in the carriage road between platforms four and five. I do hope they know what they're doing!

John Rastall (M), john. rastall@tesco. net

Have your say

You must sign in to make a comment

Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.