Type II Noise Barrier Implementation Plan

The Goal of this Implementation Plan | Cost Effectiveness | Program Costs |

The Goal of this Implementation Plan

The goad is to have a minimum of two Type II Noise Barriers advertised for construction per year. (Note: As with all projects included on the Construction Advertising Program, selected locations will be coordinated with the EOT Planning Division and the District Offices for Project Review Committee approval and inclusion on the regional Transportation Improvement Plans).

Cost Effectiveness

The Cost Effective Index (CEI) is a useful analytical calculation to determine a barrier's reasonableness by comparing the total cost of the barrier divided by the amount of noise reduction achieved and the number of homes protected.

Cost Effective Index (CEI) = Barrier Construction Cost** (IL) (# units)
IL = Insertion Loss (noise reduction in decibels)
# units = number of homes impacted by noise barrier with a noise reduction of 5 db or more
Barrier Construction Cost** = Area (ft2) * Cost ($/ ft2)
**Does not include costs of feasibility study, survey, foundation analysis, acoustical design and environmental permitting, traffic police or contract contingencies.

The CEI is calculated based upon the noise reduction received at sensitive receptors in the study zone which is defined as the area 150 meters (500 ft.) back from the edge of the roadway directly behind the barrier. Receivers in the study zone must realize at least 5 dB IL to be counted as 'protected' and included in the CEI calculation. Receivers getting less than 5 dB of noise reduction are not counted as protected. Noise barriers are designed to protect ground level exterior activity. Only the first floor dwellings of multi-family homes are included in a cost effectiveness calculation.

MassHighway has established a CEI of $2,700 developed in accordance with guidance from the FWHA and this value is consistent with that set by other State DOT's. According to FHWA, the national average spent per home for noise barriers, is between $25,000 and $30,000. Barriers are designed to meet acoustical feasibility requirements for a 10 decibel reduction in noise (Insertion Loss). Thus at $27,000 per home MassHighway is within the national average.

When the $2,700 value was set it was based upon a cost per square foot of $16 to construct a barrier. Actual barrier costs vary and examination of several recent noise barrier construction projects shows the actual cost to be $22.50 per square foot, more in keeping with today's construction costs. Applying the $22.50 back into the CEI would increase the cost spent per home to $38,000 which is above the national average.

Program Costs

The barriers in the Type II Study ranged in height from 12 to 26 feet and in length from 1200 to 7900 feet. The total cost of all 53 barriers was estimated in 1987 dollars as $45,200,000 exclusive of the cost for final acoustical design, right of way and any other environmental mitigation that may be necessary.

Analysis of the three most recently completed barriers shows an average construction cost per square foot of $22.50. Thus the cost per linear foot at an average 14 feet high is $315 or $1,633,200 per mile. The added costs of final design, Right of Way, environmental permitting, traffic police, and other construction contingencies would still apply. Therefore, in today's dollars the total cost to construct all 53 barriers is estimated at approximately $100 million.