(a) The department shall develop and implement a system of priorities for ranking the need for installation of noise attenuation barriers along freeways in the California freeway and expressway system. In establishing a priority system, the department shall give the highest consideration to residential areas which were developed prior to the opening of the freeway. If alterations have been made to the freeway since its original opening which result in a significant and measurable increase in ambient noise levels, the opening date for that segment of the freeway, for the purposes of determining priorities under this section, is the completion date of that alteration project. Other criteria for determining priorities shall include the existing and future intensity of sound generated by the freeway, the increase in traffic flow since the original construction of the freeway, the cost of building the soundwall in relation to the expected noise reduction, the number of persons living in close proximity to the freeway, and whether a majority of the occupants in close proximity to the freeway resided there prior to the time the freeway routing was adopted by the commission. The city or county in which the residential area is located shall be responsible for providing documentation to the department on the percentage of original occupants still residing along the freeway.

The actual cost of construction shall be used in determining the relative priority ranking of projects funded and constructed pursuant to subdivision (d).

(b) When all freeways have been ranked in priority order, the department shall, consistent with available funding, include in its proposed state transportation improvement program, a program of construction of noise attenuation barriers beginning with the highest priority.

In preparing the annual priority list, the department shall not add any new project to the list ahead of a project that has been funded by a city or county, or by any other public agency using public funds, and is awaiting state reimbursement pursuant to subdivision (d).

(c) The commission shall include in the estimate adopted pursuant to § 14525 of the Government Code an annual and five-year estimate of funds estimated to be available for noise attenuation barriers along freeways. If any city or county constructs a noise attenuation barrier along a freeway pursuant to subdivision (d), the commission shall allocate funds for the project in the fiscal year the project would have been eligible for funding based on the department’s priority list and the commission’s fund estimate at the time of approval of the project pursuant to subdivision (d).

(d) If any city, county, or public agency constructs a noise attenuation barrier along a freeway using public funds prior to the time that the barrier reaches a high enough priority for state funding, then, when the funding priority is reached, the department shall reimburse the city, county, or public agency without interest for the cost of construction, but the reimbursement may not exceed the cost of the department to construct the barriers. Reimbursement shall be made only if the city, county, or public agency constructs the noise attenuation barrier to the standards approved by department, follows bidding and contracting procedures approved by the department, and the project is approved by the commission.

(Amended by Stats. 1991, Ch. 1107, Sec. 1.)