Traffic engineering: Data management tools

Welcome to the second half of Week 3 of the traffic engineering module.

In the upcoming units, we built on the traffic engineering data measurement methods covered in the first half of Week 3, and covered the different tools and methodologies for effectively managing and processing the measured traffic engineering data.

As discussed, there is a wide variety of supply and demand data in the field of traffic engineering. However, our primary focus will be on dynamic data, particularly traffic flow data, such as traffic counts, which we have already covered.

Understanding the Role of Traffic Data in Engineering Analysis

Traffic data serves as a critical tool in traffic engineering, offering insights into the functioning of transportation infrastructure and informing decisions about improvements and mitigations. Traffic engineering projects can range from relatively simple analyses to complex simulations depending on the scope and scale of the project. The type of data management tools used will depend on the complexity of the task at hand.

Project Applications of Traffic Data:

Project A – Improving Traffic Flow:
Suppose an intersection experiences congestion during peak hours, and your goal is to improve traffic flow. In this scenario, traffic data can be used to develop a traffic simulation model. The simulation model would be calibrated using the traffic data, allowing you to test different scenarios, such as changes in road geometry or adjustments to traffic signal settings.

Project B – Mitigating the Impact of New Development:
Alternatively, you may be tasked with assessing the impact of a new development on an existing transportation network. For example, a new development could change traffic patterns and lead to congestion. In this case, you would use traffic data to conduct a Traffic Impact Assessment (TIA), which helps in formulating a mitigation strategy.

Traffic Impact Assessment (TIA) and Data Requirements

A TIA is a crucial tool for evaluating the effects of new developments or infrastructure changes on an existing transportation network. A comprehensive TIA requires a variety of data points to assess both the current and future conditions of the transportation system.

Key Data Categories for Traffic Impact Assessments:

Site Development Data:

• Land Use Information: Type of development (e.g., residential, commercial, industrial).
• Size and Layout: Dimensions of the development, access points, parking provisions, and internal circulation plans.
• Projected Opening Date: The timeline for the completion and operation of the development.

Traffic Data:

• Existing Traffic Volumes: Current traffic counts on adjacent roads and intersections.
• Traffic Growth Rates: Historical and projected growth rates based on regional trends.
• Vehicle Classifications: Breakdown of traffic by vehicle type (e.g., cars, trucks, buses).
• Trip Generation Rates: Estimated number of trips generated by the development, typically derived from standard sources like the Institute of Transportation Engineers (ITE).

Transport Network and Operational Data:

• Road Network Layout: Information on road geometries, lane configurations, and intersection control.
• Intersection Performance Data: Level of Service (LOS), delay times, queue lengths, and signal timings at critical intersections.
• Public Transport Availability: Proximity and frequency of public transport services.
• Non-motorized Transport Infrastructure: Pedestrian and cycling facilities, such as sidewalks and bike lanes.

Travel Behavior Data:

• Modal Split Data: The distribution of travel across different modes (e.g., private vehicles, public transport, walking, cycling).
• Trip Distribution Patterns: Origin and destination of trips within the study area.

Demographic and Socioeconomic Data:

• Population and Employment Projections: To estimate future travel demand in the surrounding area.
• Household Income and Vehicle Ownership Rates: Indicators of potential car usage and modal preferences.

Parking and Loading Information:

• Parking Demand: Existing and projected parking needs in the area.
• Loading Zones: Demand for freight and goods handling facilities.

Environmental and Policy Considerations:

• Environmental Impact Data: Including air quality, noise levels, and impacts on sensitive areas.
• Transportation Policies: Alignment with regional mobility plans, sustainability goals, and zoning regulations.

Using Traffic Counts for Traffic Impact Assessment

Traffic counts are integral to a Traffic Impact Assessment as they provide baseline data for current traffic conditions. These counts help in understanding the existing traffic flow and are used for forecasting future traffic patterns under different development scenarios.

How Traffic Counts Are Used:

1. Establishing Baseline Traffic Conditions:
   Traffic counts provide real-world data on the current volume of traffic, highlighting congestion, flow patterns, and peak travel times.
2. Calibrating Traffic Models:
   Traffic counts are used as input for traffic simulation models, helping to calibrate these models and ensure they accurately represent current traffic conditions.
3. Forecasting Future Traffic Conditions:
   By combining traffic counts with trip generation data and traffic growth rates, planners can project future traffic volumes.
4. Assessing Intersection and Roadway Performance:
   Traffic counts allow for the analysis of Level of Service (LOS) and the capacity of intersections and road segments.
5. Developing Mitigation Measures:
   Traffic counts help in evaluating mitigation strategies, such as road widening, signal timing adjustments, or new turn lanes.

Using Spreadsheets for Traffic Impact Assessments

For smaller-scale projects, Traffic Impact Assessments can be performed using spreadsheets. While more complex modeling software is often preferred for large-scale developments, spreadsheets can still be an effective tool for organizing data, performing basic calculations, and generating reports.

Key Steps in Conducting a TIA Using Spreadsheets:

1. Data Collection:
   Input baseline traffic count data, including peak-hour volumes, vehicle classifications, and trip generation rates derived from sources like the ITE.
2. Calculations:
   • Existing Traffic Analysis: Calculate the volume-to-capacity (V/C) ratio or Level of Service (LOS).
   • Trip Generation: Estimate the number of new trips generated by the development.
   • Future Traffic Volumes: Add projected new trips to baseline traffic counts.
3. Intersection Analysis:
   Assess LOS and intersection capacity to identify potential bottlenecks.
4. Mitigation Measures:
   Evaluate different mitigation strategies and assess their impact on traffic flow.
5. Growth Rate Projections:
   Use growth factors to project future traffic volumes.
6. Visualization and Reporting:
   Create graphs, charts, and tables to visualize findings.

Limitations of Spreadsheet-Based TIAs:

Spreadsheets are suitable for smaller projects but are not equipped to handle complex traffic networks or simulate dynamic traffic behaviors. For large-scale projects, traffic simulation software like Synchro or VISSIM is preferred.

Conclusion

Traffic engineering data management plays a pivotal role in Traffic Impact Assessments. By understanding and analyzing traffic counts, engineers can assess the impact of developments and design mitigation strategies. Spreadsheets are practical for smaller projects, but advanced simulation tools are needed for larger developments.

In the next unit, we will explore how to extrapolate emissions data from traffic counts to assess environmental impacts and optimize transportation systems for sustainability.