System Performance assesses the performance of the Interstate and non-Interstate National Highway System (NHS) for the purpose of carrying out the National Highway Performance Program (NHPP); assesses freight movement on the Interstate System; and assesses traffic congestion and on-road mobile source emissions for the purpose of carrying out the Congestion Mitigation and Air Quality Improvement (CMAQ) Program.
A requirement of the CMAQ Performance Measures (Traffic Congestion & Total Emissions Reductions) is the development of a CMAQ Performance Plan (CPP) to be updated biennially. The CPP includes a baseline level for traffic congestion and emissions, a description of the progress made in achieving performance measure targets, and a description of projects funded through the CMAQ program & their potential impact on achieving the targets.
CMAQ Performance Plan
Final Report, 2nd Performance Period - October 2022 to 2026
Baseline Performance Report, 3rd Performance Period - October 2026 to 2030
Traffic Congestion
This subpart is applicable to all urbanized areas that include National Highway System (NHS) mileage and have a population over 1 million that are, in all or part, designated as nonattainment or maintenance areas for Ozone (O3), Carbon Monoxide (CO), or Particulate Matter (PM10 and PM2.5) per National Ambient Air Quality Standards (NAAQS).
As the Memphis Urbanized Area, which covers parts of Tennessee, Mississippi, and Arkansas, including the Planning Areas of the Memphis Urban Area Metropolitan Planning Organization (MPO) and West Memphis MPO, meets the threshold set, the following performance measures applied to the Memphis, TN-MS-AR Urbanized Area:
- Annual hours of peak hour excessive delay (PHED) per capita
- Percentage of non-single occupancy vehicle travel
On July 30, 2026, the Transportation Policy Board (TPB) of the Memphis Urban Area MPO approved a resolution to support the 2 and 4-year targets for the Tri-State Urbanized Area. The current targets are shown in the table below:
| Memphis, TN-MS-AR Urbanized Area | |||
|---|---|---|---|
| Traffic Congestion Performance Measures | Baseline | 2-Year Target (2028) | 4-Year Target (2030) |
| Percentage of Non-Single Occupancy Vehicle Travel | 24.0% | 19.9% | 19.9% |
| Annual Hours of Peak-Hour-Excessive Delay | 8.1h | 10.8h | 10.8h |
Additional Resources
Resolution to Support the CMAQ Performance Measure Targets (05.19.2022)
Resolution to Support the Updated CMAQ Performance Measure Targets (05.23.2024)
Memphis MPO CMAQ Performance Measures Presentation
University of Tennessee PHED Analysis Presentation
Total Emissions Reduction
This performance measure is only applicable to areas that include any part of a nonattainment or maintenance area for Ozone (O3), Carbon Monoxide (CO), or Particulate Matter (PM10 and PM2.5) per National Ambient Air Quality Standards (NAAQS). This measure is limited to these areas to further the CMAQ’s program purpose of funding programs and projects that seek to satisfy the NAAQS.
As the Memphis MPO has a population greater than 1 million and is designated as maintenance for Ozone (O3) and attainment for Carbon Monoxide (CO), performance targets for this measure must be established. On July 30, 2026, the Transportation Policy Board (TPB) of the Memphis Urban Area MPO approved a resolution to support the 2 and 4-year targets for Tennessee and Mississippi. The current targets are shown in the table below:
| Tennessee (TDOT) | Mississippi (MDOT) | |||||
|---|---|---|---|---|---|---|
| Congestion Mitigation and Air Quality Performance | Baseline (FY23-26) | 2-Year Target (2028) | 4-Year Target (2030) | Baseline (FY23-26) | 2-Year Target (2028) | 4-Year Target (2030) |
| Total Emissions Reductions (VOC) KG/DAY | 1.241 | 2.188 | 4.376 | 0 | >/= 0 | >/= 0 |
| Total Emissions Reductions (NOx) KG/DAY | 22.659 | 11.790 | 23.580 | 0 | >/= 0 | >/= 0 |
Travel Time Reliability
State DOTs and MPOs are charged with reporting the measurement of travel time reliability on the Interstate and/or non-Interstate NHS. State DOTs are required to set 2-year and 4-year targets, while MPOs only have to set 4-year targets. For each of the below performance measures, MPOs can agree to support the State DOT target, or establish their own target specific to the MPO planning area:
- Percent of the Person-Miles Traveled on the Interstate that are reliable
- Percent of the Person Miles Traveled on the Non-Interstate National Highway System that are reliable
On February 16, 2023, the Transportation Policy Board (TPB) of the Memphis MPO approved a resolution to adopt the 4-year targets. On November 21, 2024, the TPB approved TDOT's updated 4-year targets. The current targets are shown in the table below:
| Tennessee (TDOT) | Mississippi (MDOT) | |||
|---|---|---|---|---|
| Travel Time Reliabililty Performance Measures | Baseline (2021) | 4-Year Target (2025) | Baseline (2021) | 4-Year Target (2025) |
| Percentage of Person Miles Traveled that are Reliable (Interstate) | 92.1% | 87.0% | 99.6% | >93% |
| Percentage of Person Miles Traveled that are Reliable (Non-Interstate NHS) | 93.4% | 87.0% | 95.0% | >85% |
Freight Movement
This differs from the Travel Time Reliability measure and it is broken down into five periods: morning peak, midday, and afternoon peak Monday – Friday, weekends and overnight for each day.
Similar to performance measures for Emissions Reduction and Travel Time Reliability, State DOTs are required to set 2-year and 4-year targets for Freight Movement, while MPOs only need to set 4-year targets. For the below performance measures, MPOs can agree to support the State DOT target, or establish their own target specific to the MPO planning area:
- Percentage of Interstate System mileage providing reliable truck travel time
On February 16, 2023, the Transportation Policy Board (TPB) of the Memphis MPO approved a resolution to adopt the 4-year targets. On November 21, 2024, the TPB approved TDOT's updated 4-year targets. The current targets are shown in the table below:
| Tennessee (TDOT) | Mississippi (MDOT) | |||
|---|---|---|---|---|
| Freight Movement Performance Measures | Baseline (2021) | 4-Year Target (2025) | Baseline (2021) | 4-Year Target (2025) |
| Truck Travel Time Reliability (TTTR) Index | 1.32 | 1.55 | 1.14 | <1.4 |
By agreeing to support the states’ (Mississippi and Tennessee) System Performance, Freight, and CMAQ targets, the Memphis MPO agrees to:
- Work with the states and relevant stakeholders to address areas of concern related to travel reliability, freight movement, traffic congestion, and emissions reduction within the metropolitan planning area
- Coordinate with the states and include the system performance, freight, and CMAQ targets for those measures in the long-range regional transportation plan (RTP)
- Integrate into the metropolitan transportation planning process, the system performance, freight, and CMAQ goals, objectives, performance measures and targets described in other state transportation plans and processes
- Include a description in the TIP (Transportation Improvement Program) of the anticipated effect of the TIP toward achieving system performance, freight, and CMAQ targets in the RTP, linking investment priorities in the TIP to those targets
Frequently Asked Questions
- What does projected non-SOV and peak hour excessive delay mean, and what is unique about it?
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This question includes a few technical terms, so it will help to break it into two parts: projected non-SOV travel and peak hour excessive delay. Both are used to better understand congestion, travel choices, and how the transportation system performs during busy times.
What does projected non-SOV mean?
Projected non-SOV means the estimated amount of work trips made by someone not driving alone. SOV stands for single-occupancy vehicle. That simply means one person driving alone in a vehicle.
Non-SOV trips may include:
- Carpooling
- Vanpooling
- Public transit
- Telecommuting or working from home
Are non-SOV projections telling people they cannot drive alone?
No. These projections do not force anyone to travel a certain way. They help planners understand how people may get to work and how travel choices can affect congestion and air quality.
A simple example: Imagine four coworkers who all live near each other and work downtown. If each person drives alone, that is four vehicles on the road. If two of them carpool, one takes the bus, and one works from home that day, fewer vehi-cles are added to rush-hour traffic. This is the kind of travel pattern non-SOV measures help agencies understand.
What is unique about this measure?
This metric is especially important because it can help carry out the Congestion Mitigation and Air Quality Improvement, or CMAQ, Program. CMAQ is a federal program that supports transportation projects that may help reduce congestion and improve air quality.
Why does this matter?
When more people have practical options besides driving alone, thetransportation system can work better for everyone. That does not mean driving alone goes away. It simply means communities can plan for more choices.
What does peak hour excessive delay mean?
Peak hour excessive delay means the extra travel time people experience during the busiest parts of the day, usually morning and afternoon rush hours. It is measured in 15-minute intervals when traffic speeds drop below certain thresholds, such as below 20 mph or below 60% of the posted speed limit. In plain language: it measures how much extra time people spend stuck in traffic.
A simple example: If your normal trip to work takes 20 minutes, but during rush hour it takes 35 minutes, the extra 15 minutes is delay. When that kind of delay happens across many people and many trips, agencies can measure it over time.
What is unique about this measure?
Peak hour excessive delay is unique because it measures annual hours of traffic delay per person. That means it does not just show where congestion happens. It helps estimate how much time people are losing because of congestion.
Why are non-SOV and peak hour excessive delay connected?
They both help tell the story of how well the transportation system is moving people. Non-SOV looks at travel choices. Peak hour excessive delay looks at the extra time caused by congestion.
Together, they help agencies ask:
- Are people spending more time stuck in traffic?
- Are there realistic travel options besides driving alone?
- Where might transit, carpooling, signal timing, road improvements, or telework strategies help?
- Which investments could reduce delay and improve air quality?
Bottom line?
Projected non-SOV and peak hour excessive delay help explain how people travel and how much extra time congestion adds to daily trips. These measures help communities plan for better travel options, less delay, and improved air quality.
- What does projected emissions and travel time reliability mean?
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These measures help transportation agencies understand two different but related issues: how transportation affects air quality and how predictable travel times are for everyday trips.
What does projected emissions mean?
Projected emissions are the forecasted amount of air pollutants expected to come from transportation activity. This can include pollution from cars, trucks, buses, and other vehicles using the transportation system. The purpose is not to blame individual travelers. It is to understand how future travel patterns may affect air quality and where improvements may be needed. This measure looks at the projected reduction in emissions from projects funded through the CMAQ program.
Are projected emissions exact numbers?
No. They are estimates based on available data, travel trends, vehicle activity, and planning assumptions. Like a weather forecast, they help agencies prepare and make better decisions, even though the future can change.
A simple example: If a community expects more people, more jobs, and more traffic in the future, it may also expect more vehicle emissions unless improvements are made. Those improvements could include better traffic flow, more transporta-tion choices, cleaner vehicles, or projects that reduce unnecessary idling.
Why does this matter?
Air quality affects the health and quality of life of a community. Projected emissions help agencies understand whether transportation investments are helping reduce pollution or whether additional strategies may be need-ed.
What does travel time reliability mean?
Travel time reliability means how consistent a trip is from day to day. It is not just about whether a trip is long or short. It is about whether people can count on the trip taking about the same amount of time most days.
A simple example: A parent may need to leave home at 7:30 a.m. to drop a child off at school and get to work on time. If that trip usually takes 20 minutes, it is reliable. But if it takes 20 minutes one day, 45 minutes the next day, and 30 minutes the day after that, it becomes harder to plan. That is what travel time reliability measures: predictability.
Why does this matter?
Because reliable travel helps people plan their lives. It affects:
- Getting to work on time
- School drop-off and pickup
- Medical appointments
- Freight and deliveries
- Emergency response
- Transit schedules
- Business operations
What can make travel time unreliable?
- Heavy traffic
- Crashes
- Road work
- Weather
- Special events
- Bottlenecks
- Poor signal timing
- Limited route options
Why are these projections included in planning?
Projected emissions and travel time reliability help agencies understand future conditions before problems grow. They help identify where investments may improve traffic flow, reduce pollution, and make daily trips more predictable.
Bottom line?
Projected emissions help agencies understand transportation’s future impact on air quality. Travel time reliability helps measure whether trips are predictable. Together, these measures help communities plan for cleaner, more depend-able travel.
Additional Resources
