(a) From the funds programmed pursuant to Section 188 for regional improvement projects, the commission shall approve programs and program amendments, so that funding is distributed to each county of County Group No. 1 and in each county of County Group No. 2 during the county share periods commencing July 1, 1997, and ending June 30, 2004, and each period of four years thereafter. The amount shall be computed as follows:

1. (1) The commission shall compute, for the county share periods all of the money to be expended for regional improvement projects in County Groups Nos. 1 and 2, respectively, as provided in Section 188.
2. (2) From the amount computed for County Group No. 1 in paragraph (1) for the county share periods the commission shall determine the amount of programming for each county in the group based on a formula that is based 75 percent on the population of the county to the total population of County Group No. 1 and 25 percent on state highway miles in the county to the total state highway miles in County Group No. 1.
3. (3) From the amount computed for County Group No. 2 in paragraph (1) for the county share periods the commission shall determine the amount of programming for each county in the group based on a formula that is based 75 percent on the population of the county to the total population of County Group No. 2 and 25 percent on state highway miles in the county to the total state highway miles in County Group No. 2.

(d) For the purposes of this section, funds programmed shall include the following costs pursuant to subdivision (b) of Section 14529 of the Government Code:

1. (1) The amounts programmed or budgeted for both components of project development in the original programmed year.
2. (2) The amount programmed for right-of-way and right-of-way support costs in the year programmed in the most recent state transportation improvement program. If the final estimate is greater than 120 percent or less than 80 percent of the amount originally programmed, the amount shall be adjusted for final expenditure estimates at the time of right-of-way certification.
3. (3) The engineer’s final estimate of project costs, including construction support, presented to the commission for approval pursuant to Section 14533 of the Government Code in the year programmed in the most recent state transportation improvement program. If the construction contract award amount is less than 80 percent of the engineer’s final estimate, excluding construction support, the department shall notify the commission and the commission may adjust its project allocation accordingly.
4. (4) Project costs shown in the program, as amended, where project allocations have not yet been approved by the commission, escalated to the date of scheduled project delivery.

(e) Project costs shown in the program may not be changed to reflect any of the following:

1. (1) Differences that are within 20 percent of the amount programmed for actual project development cost.
2. (2) Differences that are within 20 percent of the amount reported at the time of allocation pursuant to paragraph (2) of subdivision (d) for actual right-of-way costs calculated at the time of acceptance of a project construction contract.
3. (3) Construction contract award amounts, except when those amounts are less than 80 percent of the engineer’s final estimate, excluding construction support, and the commission has adjusted the project construction allocation.
4. (4) Changes in construction expenditures, except for supplemental project allocations made by the commission, including supplemental allocations made pursuant to subdivision (b) of Section 188.9.