They may be cumbersome and large but drawings and plans were originally done for a very good reason and continue to be done this way in some cases. This is because all the details are intricate and have to be covered and each and every thing has to be accuracy perfect. However these days, large format documents pose a tiny problem for these organizations which use them.
Their industries are moving forward and that which is becoming increasingly electronic whilst these large format items remain in the corner and become increasingly tricky to use and damaged with time and excessive use. However these days it is possible to convert these files into formats which can be read and even edited in the most popular CAD Conversions applications such as AutoCAD. CAD conversion by means of a document scanning company is the best way that this can be done.
Nearly all document scanning companies have a scanner that can handle documents of the size of an architects drawing or an engineering plan and the scanning could be a comparatively simple, albeit fairly slow procedure.
After the scans are completed, depending on who the company you go with is and what they can provide, the scans will be rendered by hand and saved to a CAD converted format such as the DXF file, or an automatic alternative could be available. The automatic service can lack precision, but it is always best to request a sample be produced to find out what you would end up with.