2 Del. Admin. Code § 3.6
Any major residential development proposed to be constructed in the proximity of any roadway with a functional classification of principal arterial, freeway or interstate will be required to perform a noise analysis and shall meet the requirements of this regulation with regard to the following:
For residential projects adjacent to existing transportation facilities or requiring off-site improvements to transportation facilities, it is the developer's responsibility to evaluate noise levels and their impacts to proposed and existing development.
The Federal Highway Administration (FHWA) has issued regulations for noise evaluation in 23 CFR 772, Procedures for Abatement of Highway Traffic Noise and Construction Noise. DelDOT has developed a noise policy to implement of the requirements of the Federal Highway Administration (FHWA) Noise Standards. Please refer to Delaware Policy Implement No. D-03 for guidance regarding data collection, noise prediction, impact analysis, abatement measures and other procedures used to evaluate highway traffic and construction noise.
The noise abatement criteria, depicted in Table 1, are values which, when approached or exceeded, require the consideration of traffic noise abatement measures. The developer should consider noise mitigation when traffic noise levels exceed one decibel below the values shown in Figure 3.6.3-a.
Figure 3.6.3-a: Noise Abatement Criteria
Development projects fronting roadways that are designated on DelDOT's Functional Classification Map as a principal arterial, a freeway or an interstate will be required to conduct a noise impact study utilizing the FHWA Traffic Noise Model (TNM) criteria based upon the existing and/or forecasted traffic on the roadway. The noise impact study will predict and evaluate future traffic noise levels for the impacted receptors proposed by the development. In performing the TNM analysis, the developer shall utilize the average pavement type unless an alternative pavement type is approved for use by DelDOT. The developer is required to utilize the TNM to determine at what point during the year would yield the worst traffic noise impacts and utilize those traffic characteristics in performing the noise impact modeling. The study should include examining mitigation measures to shield the future abutting property owners from noise impacts or to reconfigure the site to place less sensitive receptors adjacent to the roadway.
DelDOT will review the noise impact study and analyze proposed mitigation measures as noted in Delaware's Highway Transportation Noise Policy. In lieu of installing mitigation measures, the Department may suggest that the Developer redesign the site plan by changing impacted areas from sensitive land uses to non-sensitive land uses. The DelDOT letter of no objection to record the development will be contingent upon a layout that has been designed to minimize noise impacts to the satisfaction of DelDOT following the full build-out of the site.
DelDOT will require that the Record Plans for proposed land development projects include provisions for highway noise abatement if the results of the noise analysis indicate an adverse noise impact will result. The security that is required to indemnify the construction agreement for the entrance shall be calculated including the estimated cost to construct the noise mitigation measures specified on the Record Plan.
Although the local land use authority is responsible to ensure that all noise mitigation measures are constructed prior to the issuance of any Certificates of Occupancy for impacted structures, DelDOT will be responsible for insuring that the noise mitigation measures are constructed prior to accepting the street construction. The plans for streets serving impacted residences must include construction plans for noise barriers and/or walls. Noise mitigation measures shall be designed and constructed to meet DelDOT requirements. The security will not be released by the Department until the noise mitigation measure is constructed to DelDOT standards. Maintenance of any fence, berm or noise wall will remain the responsibility of the Developer or community, as described in a maintenance agreement with DelDOT.
If a development project requires an off-site improvement which requires the addition of one or more through lanes, the Developer of the land development project will be required to conduct a noise impact study utilizing the FHWA Traffic Noise Model (TNM) criteria based upon the forecast traffic on the improved section of roadway for any road that is designated in whole or in part on the DelDOT Functional Classification Map as a principal arterial, a freeway or an interstate. The noise impact study will predict and evaluate future traffic noise levels for the design that is under consideration. In performing the TNM analysis, the developer shall utilize the average pavement type unless an alternative pavement type is approved for use by DelDOT. The developer is required to utilize the TNM to determine at what point during the year would yield the worst traffic noise impacts and utilize those traffic characteristics in performing the noise impact modeling. The study should include examining mitigation measures to shield current abutting property owners from noise impacts.
DelDOT will review the noise impact study and analyze proposed mitigation measures as noted in Delaware's Highway Transportation Noise Policy. The DelDOT letter of no objection to record will be contingent upon a mitigation plan that has been designed to minimize noise impacts to the satisfaction of DelDOT following the construction of the off-site improvements.
DelDOT will be responsible for insuring that the noise mitigation measures are constructed prior to accepting the street construction. The plans for streets serving impacted residences must include construction plans for noise barriers and/or walls. Any abatement measures are to be constructed by the developer concurrently with the offsite improvements. Noise mitigation measures shall be designed and constructed to meet DelDOT requirements. The security will not be released by the Department until the noise mitigation measure is constructed to DelDOT standards. Maintenance of any fence, berm or noise wall adjacent to an off-site improvement and within DelDOT's Right-of-Way will become the maintenance responsibility of the Department.
The criteria below shall be used by DelDOT to ensure that noise mitigation measures are both reasonable and feasible. The feasibility and reasonableness of a potential noise abatement measure must be evaluated before the Department will examine detailed noise mitigation concepts.
The evaluation of the feasibility of a noise mitigation measure deals primarily with engineering considerations. The Developer will be required to design all noise mitigation measures with the intention of achieving a noise level below the criteria shown in Figure 3.6.3-a.
However, there are factors that may limit the ability to achieve substantial noise reduction. These factors include but are not limited to the following:
If the developer is unable to meet the noise levels shown in Figure 3.6.3-a due to the limiting factors listed above (or other limiting factors), DelDOT's Subdivision Engineer may waive the requirement. If the requirement is waived, the record plan should clearly identify the proposed locations that will not meet the noise level requirements shown in Figure 3.6.3-a.
The Department will evaluate a number of factors when determining if a noise mitigation measure is reasonable. The criteria that shall be used to determine the reasonableness of a noise mitigation measure are listed below:
2 Del. Admin. Code § 3.6
15 DE Reg. 551 (10/01/11)
16 DE Reg. 1199 (5/1/2013)
18 DE Reg. 240 (9/1/2014)
18 DE Reg. 709 (3/1/2015)
19 DE Reg. 938 (4/1/2016)
23 DE Reg. 378 (11/1/2019) (Final)