Acknowledgements

Except for third party materials and otherwise stated (see terms and conditions [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] ), this content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Licence

Grateful acknowledgement is made to the following sources for permission to reproduce material within this course

Course image: Tom Page in Flickr made available under Creative Commons Attribution-ShareAlike 2.0 Licence.

Figure 3 H. R. Wallingford Limited

Figure 4 © London Transport Museum

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