Whenever the board approves a county local road program project under this chapter it shall determine the amount of county local road program funds to be allocated for such project. The allocation must be based upon information submitted by the county seeking approval of the project and upon such further investigation as the board deems necessary. The board shall adopt reasonable rules pursuant to which county local road program funds allocated to a project may be increased upon a subsequent application of the county constructing the project. The rules adopted by the board must take into account, but are not limited to, the following factors:
(1) The financial effect of increasing the original allocation for the project upon other county local road program projects either approved or requested;
(2) Whether the project for which an additional allocation is requested can be reduced in scope while retaining a usable segment;
(3) Whether the original cost of the project shown in the applicant's original submittal was based upon reasonable engineering estimates; and
(4) Whether the requested additional allocation is to pay for an expansion in the scope of work originally approved.