Spring Ranch I-70 Noise Abatement

Acknowledgements

Project Advisors: Alina Handorean and Elizabeth Reddy

Technical Advisors: Andres Guerra and Matt Whitney

Donations Made by: Spring Ranch HOA

Video

Elevator Pitch

The purpose of the sound wall is to create a barrier between the noise pollution coming off of Interstate 70 and the residents of the Spring Ranch community. The wall was designed to be installed in individual concrete sections in order to make the construction process as noninvasive as possible. The stakeholders of the project include the Colorado Department of Transportation (CDOT), the Spring Ranch residents, and I-70 commuters. In designing the wall, all significant force calculations were carried out to in order minimize any possible risks for the proposed wall design. This design provides a fair solution for each stakeholder, most importantly providing a significant amount of noise reduction to the Spring Ranch neighborhood.

Using Noise3D, a 3-dimensional noise simulation program, the Spring Ranch Neighborhood, I-70, and the sound wall were modeled. The model with no sound wall implemented matched the sound intensity levels of measurements taken by the team at the beginning of the design process, confirming that the program was accurate. At present day traffic volume values, a 20 ft. sound wall reduced the average sound intensity level by 4.28 dB, below the CDOT requirement of at least 5 dB of sound reduction. Traffic volume data pulled from a CDOT database allowed for future projections of highway noise levels, which are expected to increase at a steady rate, as the population of Colorado continues to increase. Starting in the year 2040, the 20 ft. sound wall would be considered effective under CDOT code, as it results in an average of 5.10 dB in sound intensity level reduction.

Design Approach

Design Solution

The clients requested a reasonable solution to the excess sound pollution coming from I-70, the adjacent interstate to the Spring Ranch community. The team met with the project client a number of times to discuss their wants and needs for the design of the sound wall. More so than the immediate benefits of the sound wall, the client was enthusiastic about the future projections of the effectiveness of the sound wall against the increase in traffic on the interstate.

Some concerns that were mentioned by the client include the restrictions of the sound wall construction along I-70 due to the location of Spring Ranch. The neighborhood is accessed via a direct exit from the highway, therefore posing design restrictions that prevent a wall from being built along some of the loudest and closest sections of the interstate. Despite this obstacle, the wall design proposed is still projected to provide noise pollution mitigation for a majority of the properties in the area.

The main area of concern of our project is that the simulated wall in Noise3D provides only the minimum amount of sound reduction upon immediate implementation. Our minimum goal was to block five decibels of sound from the Spring Ranch community, and for current day traffic volumes, the wall would not reach the 5 dB reduction goal. The average decibel reduction with the implementation of a 20 foot sound barrier is 4.28 dB, which is 0.72 dB less than the required 5 dB that CDOT requires for a sound wall to be installed. This average value was the result of a number of samples taken throughout the Spring Ranch Community, and it should be noted that the homes farthest from the interstate already experience lower noise pollution levels than the homes that are adjacent to the highway. The sound wall will have a more significant effect on the homes closest to the highway that already experience the highest sound pressure levels. Additionally, the benefits of the sound wall will increase over time as the traffic increases on the interstate. Starting around the year 2040, using the projected highway volume data, the wall would surpass the 5 dB sound reduction limit and would be a feasible method to mitigate the sound emitted from I-70 into the Spring Ranch Neighborhood.

The final design of the wall incorporated three sections: The traffic, or “Jersey” barrier, two identical cement panels stacked vertically, and a steel H section cast into a cement pylon. The wall is designed to be easily mass produced, therefore have a streamlined and smooth integration.

Next Steps

This project could move forward by continuing to analyze the effectiveness of the sound wall in different software programs. Initially, two noise modelling software programs were going to be used and compared. This would have given us a more accurate idea of how much sound would be reduced by the noise wall. In the end, only one program was used (Noise3D). Since our designed noise wall did not reduce the sound as much as the group expected, it would be interesting to see if another software had a different result. If other software programs had similar results, another solution could then be considered.

Individual noise walls were one of the solutions mentioned in the preliminary design report, and should still be considered as viable solutions for residents that would like a shorter term solution.

Additionally, it has been discussed with our client that it would not hurt to take our current findings to CDOT to see if they think our current solution is feasible.

Meet the Team