The London and Birmingham Railway
Shown here is the original civil engineering record for the construction of Boxmoor (Hemel Hempstead) Skew Bridge from 1836. This show the types and quantities of materials used at approximately monthly intervals.

Compare the drawing above made by J. C. Bourne just after construction (c1839) with the photograph below taken in 2007. The drawing is photographically accurate. The implication is that other contemporary drawings of the line (e.g. the famous depiction of Tring Cutting with its barrow runs) by Bourne, for which we have no photograph, can be relied upon as accurate. Today the original Boxmoor Skew bridge is hemmed in by a later addition railway bridge built to provide extra tracks.
For the Google Street View of this location CLICK HERE.