Here are some books you could read which would form an excellent background for your research:
Armstrong J., (2008), 'The Railroad: What It Is, What It Does’, 5th Edition edited by William C. Vantuono. Simmons-Boardman Books, Inc.; ISBN: 978-0-911382-58-7
Bonnett, Clifford F. Practical railway engineering. London: Imperial College Press, 2005.
Connor, P., Harris, N. & Schmid, F. (2015), 'Designing and Managing Urban Railways’, published jointly by A & N Harris and University of Birmingham, 2015.
Profillidis, V.A., (2014), 'Railway management and engineering'. Ashgate Publishing, Ltd.
As regards consruction techniques - are you talking about new railways?