I am doing my thesis work related to mass transportation so mono rail could be one option. I have tried but couldn't get materials related to cost estimate .
You should first declare what type of costs you want to estimate in your thesis (Infrastructural, Operational, or External Costs). But I think these references would be helpful:
[1] Dings, J. M. W., Sevenster, M. N., & Davidson, M. D. (2003). External and Infrastructure Costs of Road and Rail Traffic analysing European studies. available in: http://www.ce.nl/?go=home.downloadPub&id=79&file=4343_defreportJD.pdf
[2] Korzhenevych, A., Dehnen, N., Bröcker, J., Holtkamp, M., Meier, H., Gibson, G., … Cox, V. (2014). Update of the Handbook on External Costs of Transport. final report for the European Commission: DG-MOVE. https://doi.org/Ref: ED 57769 - Issue Number 1
[3] Litman, T. (2015). Evaluating Public Transit Benefits and Costs. available in: www.vtpi.org/tranben.pdf