Governments and their subdivisions are very careful in making tollway commitments. Public agencies are very selective in projects they will finance. As explained above, public agencies ration their investments to ensure success of the investment. They ensure that the tollway revenues will comfortably exceed debt service in any foreseeable scenario.
The actual economic value for a debt-financed tollway is very likely to be lower than that calculated with the coupon rate of debt used as the discount rate. A second logical consequence is that any front-end or periodic concession payment must not be too large. Calculated economic value which is not paid out is viewed by the holders of the debt to be a safety net supporting the debt service due them. It acts like equity in the case of PPP's.
No one should confuse project competition with higher front end or periodic concession payments. The latter are easy to inflate but doing so takes safety margins away from the concessionaire's financial structure.