Master FHWA's Traffic Noise Model Coding

Master FHWA's Traffic Noise Model Coding

Table of Contents:

1. Introduction
2. Data Collection for TNM Model Development 2.1. Project Limits and Plans 2.2. Future Build Condition 2.3. Existing Condition 2.4. Building Footprints 2.5. Geo-Referenced Aerial Mapping 2.6. Topographic Elevation Data 2.7. Traffic Volume Data 2.8. Field Measurements 2.9. Coordinate System Validation 2.10. Identifying Topographic Layers
3. Recommended Best Practices for TNM Model 3.1. Accessing Contour Resources 3.2. Utilizing USGS and ESRI Data
4. Assembling the Project and Organizing CAD Data 4.1. Confirming CAD Layers Overlay Correctly 4.2. Coordinate System Validation 4.3. Turning On/Off Topographic and Aerial Layers
5. Traffic Data Requirements for TNM Model
6. Surveying Locations of Sources and Receivers 6.1. Sensitive Use Locations 6.2. Commercial and Undeveloped Areas 6.3. Extending Model Geographic Extents
7. Modeling Principles and Acoustical Model
8. Drafting TNM Model Objects
9. Conclusion

Title: Developing a TNM Model from CAD DXF to TNM

Introduction: Developing a Traffic Noise Model (TNM) from CAD DXF to TNM involves several steps and considerations. This article will provide a step-by-step guide on how to collect the necessary data, validate the coordinate system, organize CAD data, and draft TNM model objects. We will also discuss modeling principles and acoustical models, as well as highlight best practices for creating a TNM model. By following this guide, you will be able to create an accurate and comprehensive TNM model for traffic noise analysis.

1. Data Collection for TNM Model Development

Data collection is a crucial step in developing a TNM model. It involves gathering various types of information, including project limits, plans, existing conditions, traffic volume data, and topographic elevation data. Here are the key aspects to consider:

1.1. Project Limits and Plans

To start the TNM model development process, You need the project limits and plans in CAD or DGN format. These will serve as the basis for the future build condition and existing condition.

1.2. Future Build Condition

The future build condition refers to the planned construction or development within the project limits. It is essential to have accurate information about the future build condition to model the potential noise impacts effectively.

1.3. Existing Condition

Understanding the existing condition is crucial for accurate noise modeling. This includes information about building footprints, which helps determine the receiver locations. Additionally, having geo-referenced aerial mapping and topographic elevation data is highly beneficial.

1.4. Building Footprints

Building footprints provide valuable information about the receiver locations. By knowing the exact positions of buildings, you can accurately place receivers in the TNM model.

1.5. Geo-Referenced Aerial Mapping

Geo-referenced aerial mapping serves as a useful resource for visualizing the project area in a three-dimensional Context. It helps in accurately coding the TNM model objects.

1.6. Topographic Elevation Data

Topographic elevation data is essential for adding the three-dimensional element to the TNM model. It should be geo-referenced to ensure accurate representation.

1.7. Traffic Volume Data

For a comprehensive TNM model, you need traffic volume data, including vehicle volumes, truck percentages, and speed for each roadway. This data will be used to specify the source level strength in terms of vehicle volumes.

1.8. Field Measurements

To validate the existing conditions model, field measurements from short-term noise monitoring sites and simultaneous traffic counts are required. These measurements should follow specified protocols, such as the Caltrans protocol.

1.9. Coordinate System Validation

When assembling the project, it is crucial to ensure that the coordinate system is valid for all layers. This includes confirming the use of the correct units (English or metric) and checking the coordinate system's accuracy.

1.10. Identifying Topographic Layers

Identifying topographic layers and geo-referenced aerial layers within the CAD data is essential. These layers can be turned on and off as needed while coding TNM objects. Having three-dimensional topographic layers saves time but is not always readily available.

By collecting and organizing the necessary data, you will have a solid foundation for developing a TNM model.

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