In a Nutshell:

• Michigan ranks 40th in the nation for overall road system condition according to the 2025 update of the Citizens Research Council’s Road System Condition Index.
• The 2025 Index methodology uses ten key metrics reflecting bridge and pavement condition from Federal Highway Administration data (compared to 17 component metrics in the previous assessment). The refined approach successfully captures broad system conditions while being easier to understand.
• Seven condition metrics used in the 2025 assessment were also used in the 2024 assessment. An evaluation of these individual metrics show a mix of improvement and regression.

In April 2024, the Citizens Research Council introduced the Road System Condition Index, ranking Michigan 40^th out of 50 states. This 2025 update adopts the newest federal data and a simplified methodology that reduces redundancy and emphasizes the most reliable available data. Despite these changes, the condition of Michigan’s roads again ranks 40^th nationally.

Overview of Index and Ranking Methodology

The 2025 Road System Condition Index combines five broad measures of bridge and pavement conditions for each state as reported by the Federal Highway Administration (FHWA). Each state is assigned a component index score based on the percentage of infrastructure in both good and poor condition, resulting in ten component metrics and related index scores. These component index scores are then combined with a simple average to determine each state’s final Road System Condition Index score and ranking.

The Component Metrics

Bridge Infrastructure Condition on All Public Roads

Bridge data is drawn from the FHWA National Bridge Inventory (NBI), which requires routine inspections and provides reliable national data. The NBI provides bridge conditions both by count and deck area. Our Index uses the condition by area data to better assess overall statewide bridge infrastructure condition. By this method, larger, more critical bridges are emphasized.

In 2024, Michigan reported 27.2 percent of all public road bridges in good condition by deck area, ranking 40^th nationally and last among peer states. (Michigan’s peer states are noted in bold font in Tables 1-5 and 7.)

Michigan reported 7.8 percent of public road bridge infrastructure in poor condition by deck area, ranking 41^st nationally. Among peer states, only Illinois reported a larger percentage of bridge infrastructure in poor condition (see Table 1).

Table 1
Bridge Conditions by Deck Area on All Public Roads, Data Year 2024

Source: FHWA National Bridge Inventory, 2024

Pavement Roughness on Federal Aid Eligible Network

Pavement condition data is not available for all public roads within Michigan or any state. The most extensive data set on pavement condition covers routes that are eligible for federal highway funds. Michigan’s Federal Aid Eligible (FAE) network includes only about a third of public roads by length, but these roads carry about 90 percent of traffic within the state.¹

In 2023, Michigan reported 48.6 percent of FAE routes in good condition by roughness, ranking 24^th nationally and 5^th of an 11-state peer group. Michigan is not performing as well in preventing FAE pavement from falling into poor condition. The state reported 20.8 percent of the FAE network in poor condition in 2023, ranking 31^st nationally and 8^th among peer states (see Table 2).

Table 2
Roughness Condition by Centerline-miles on Federal Aid Eligible Roads, Data Year 2023

Source: FHWA Table HM-47i, 2023²

Daily Traffic by Pavement Roughness on the National Highway System

The National Highway System (NHS) is a subset of the FAE network, including all Interstates and other major routes determined to be of national importance. While the NHS includes only about 5.3 percent of Michigan’s public road network by route mile, it carries more than half of all traffic within the state.

For these critical routes, FHWA not only provides pavement roughness data, but also provides average daily traffic (ADT) as a percentage of travel by pavement condition. This provides a useful measure of how a state’s roads are typically experienced by drivers.³

Michigan reports that 63.5 percent of NHS average daily traffic occurs on pavement in good condition. This ranks 36^th nationally and 8^th among an 11-state peer group. Ten (10.0) percent of Michigan’s NHS traffic occurs on pavement in poor condition, also ranking 36^th nationally and 8^th among peer states (see Table 3).⁴

Table 3
Average Daily Traffic on National Highway System by Pavement Roughness, Data Year 2023

Source: FHWA Table HM-47a, 2023

Interstate Condition by the Federal Pavement Condition Metric

The most comprehensive pavement condition metric on the NHS is available through the FHWA Transportation Performance Management (TPM) program. This program was initiated to encourage states to adopt strategic data-based approaches to asset management.

States report the percentage of NHS lane miles in good and poor condition using the standardized federal pavement condition metric (PCM). The PCM is based on a combination of standardized individual pavement condition metrics (IRI, cracking, rutting, and faulting). Each underlying metric must be measured in good condition for the resulting PCM score to be good. If two or more metrics are rated poor, the resulting PCM for that pavement is determined poor. Otherwise, the pavement is judged to be in fair condition.

TPM data is reported separately for Interstate and non-Interstate NHS routes. Michigan reports 70.4 percent of Interstate lane-miles in good condition by PCM, ranking 17^th nationally and 7^th in an 11-state peer group. States generally keep Interstate pavement in relatively good condition. In fact, five states report no Interstate pavement in poor condition by PCM. Michigan reports 1.8 percent of Interstate pavement in poor condition by PCM, ranking 45^th nationally and last among peer states (see Table 4).

Table 4
Federal Pavement Condition Metric by Lane-miles on Interstate System, Data Year 2022

Source: FHWA Transportation Performance Management State Performance Dashboard and Reports
Note: Data Collected in 2022 except Michigan which has not yet reported 2022 Interstate PCM data. Michigan’s data was collected in 2021.

Non-Interstate NHS Condition by the Federal Pavement Condition Metric

Michigan’s non-Interstate NHS routes carry nearly a third of traffic in the state—more than Interstate routes. This includes large arterials such as routes labeled “M” (e.g., M-43) and “US” (e.g., US-23). States generally do not maintain non-Interstate NHS routes quite as well as Interstate routes, and this is reflected by the PCM data.

Michigan reports 41.5 percent of non-Interstate NHS pavement in good condition by PCM, ranking 22nd nationally and 5th among an 11-state peer group (see Table 5). Michigan is not performing as well in preventing non-Interstate NHS routes from falling into disrepair. The state reports 8.8 percent of non-Interstate NHS lane-miles in poor condition, ranking 48th nationally and last among peer states.

Table 5
Federal Pavement Condition Metric by Lane-miles on Non-Interstate NHS Routes, Data Year 2022

Source: FHWA Transportation Performance Management State Performance Dashboard and Reports
Note: Data Collected in 2022 except Ohio which has not yet reported 2022 non-Interstate PCM data. Ohio’s data was collected in 2021.

2025 Road System Condition Index Scores and Rankings

Our initial approach to creating a State Road System Condition Index used 17 unique metrics combined with a weighted average. This 2025 update has reduced redundancy and simplified the methodology, which allows for easier comprehension of the final Index score while retaining the ability to derive a meaningful ranking. The component index scores are based on the range of data reported by all 50 states, with the top-performing state scoring 100, and the bottom-performing state scoring zero. A summary of the condition data used to create the final Road System Condition Index score is provided in Table 6.

Table 6
Metrics Contributing to the Final Road System Condition Index Score

Across the ten metrics assessed, Michigan’s average peer state rank is 8.4 among the 11 states, and average national rank is 34^th. However, the usefulness of the indexing method is that each metric is assigned a component index score based on the range of data reported all 50 states. The ten component index scores are then combined with a simple average to derive the final Road System Condition Index score. This accounts for clustering and skewness of the data to more fairly rank states against each other as a comprehensive system condition assessment. The average of Michigan’s ten component index scores is 50.3, resulting in a national rank of 40^th and below all peer states except Illinois (see Table 7).

Table 7
2025 State Road System Condition Index Scores and Overall Ranking

Michigan’s overall rank of 40^th remains unchanged between the 2024 and 2025 assessments. Due to the changes in Index scoring methodology between 2024 and 2025, we cannot state with certainty that Michigan has made no progress compared to other states. Furthermore, the index scoring approach is a method of relative comparison between states and thus does not show if a state has made improvements to its network between years in absolute terms. However, seven of the ten component metrics used in the 2025 Index directly overlap seven of the 17 metrics used in the 2024 assessment, allowing for direct comparison of these metrics (see Table 8).

Table 8
Michigan’s Raw Data, Component Index Scores, and National Rank for Metrics Used in Both the 2024 and 2025 Road System Condition Index Assessments

As shown in Table 8, for the seven metrics that overlap between the 2024 and 2025 road system condition assessments, Michigan reports a mix of improvement and regression.

For roughness on the FAE network in poor condition, Michigan reduced FAE roads in poor condition by 0.9 percent—an improvement in absolute terms. However, Michigan’s component index score declined slightly from 61.9 to 56.8. Each component index score is calculated based on the range of data reported by all 50 states. (Michigan’s reduced component index score in this category means that Michigan’s reported data is slightly closer to the lowest performing state than the top performing state in the updated assessment.) Michigan’s relative performance among all states has declined by one ranking, from 30^th to 31^st. This all suggests that while Michigan has reduced FAE routes in poor condition by measured roughness, many states have reported greater improvement by this metric.

For average daily traffic (ADT) by pavement roughness (IRI) on the NHS, Michigan’s data changed very slightly between assessments. NHS traffic over good pavement declined by 0.5 percent (a slight regression), while traffic over poor pavement was reduced by 0.2 percent (a slight improvement). For both categories, Michigan’s component index scores declined slightly, yet Michigan’s overall rankings in both percentage-good and percentage-poor metrics are unchanged at 36^th.

By the federal Pavement Condition Metric (PCM) on Interstate highways, Michigan’s raw data remains unchanged. This is because Michigan is the only state that has not provided updated data to the federal Transportation Performance Management System. Thus, this assessment compares Michigan’s condition data collected in 2021 to all other states’ data collected in 2022.

For Interstate lane-miles rated good by PCM, Michigan’s component index score declined slightly (by 0.4) to 80.6, but Michigan’s ranking improved from 18^th to 17^th. This is Michigan’s highest component Index score and ranking of all ten metrics assessed. For Interstate lane-miles in poor condition, Michigan’s component index score improved slightly by 1.2, but Michigan dropped one ranking to 45^th nationally.

The most likely explanation for Michigan’s failure to report Interstate PCM data is that much of Michigan’s Interstate network was under construction in the 2022 reporting year (related to the Rebuilding Michigan bond funding). When Michigan’s updated data is reported, the state may see a meaningful improvement by this measure.

For non-Interstate NHS lane-miles in good condition, Michigan reported a very slight decline of 0.1 percent (a regression). However, Michigan’s component index score for this metric improved slightly, and its national ranking remains unchanged at 22^nd. Michigan reduced non-Interstate NHS lane-miles in poor condition by 0.1 percent (a slight improvement). However, Michigan’s progress on this metric appears to lag many other states, as Michigan’s component index score declined from 32.8 to 30.4 and the state dropped one ranking to 48^th nationally. This is Michigan’s lowest component ranking.

Although the 2025 update to the Road System Condition Index assessment has incorporated updated data and a refined methodology, most states’ final ranking changed very little, if at all. This is expected because the condition of a state’s entire road network changes relatively little from year to year.

The consistency between years also emphasizes the power of the index scoring method of comparing states. The 2025 Road System Condition Index methodology was simplified compared to 2024—reducing the number of component metrics included from 17 to ten. The similarity of results from 2024 to 2025 confirms that this index scoring method provides an accurate and meaningful assessment of road systems conditions across states. This simplified method can be used going forward to track Michigan’s progress over time and compared to other states in future years.

Notably, there is a time lag in condition data reported at the national level; the rankings provided here reflect data years ranging from 2022 and 2024 (depending on the metric). As we described in our award winning March 2025 report, A Data-Driven Assessment of Michigan’s Road Program, Michigan’s road infrastructure has generally seen gradual improvement since 2016. It is likely that current conditions in 2025 have improved compared to the 2022-2024 data available for this assessment. Continued progress in reported system conditions may notably improve Michigan’s national ranking, and we expect future updates in available data to show this.

Summary

We have provided a comprehensive Road System Condition Index score to conclude that Michigan ranks 40^th nationally among all 50 states in pavement and bridge conditions. This effort is a continuation of research introduced in April 2024. In this current iteration, we have updated the data to include the most recently available, as well as simplify the methodology to make the results easier to understand.

Our research establishes that Michigan’s overall road system condition ranks towards the bottom-end of states, though far from the worst.

Upcoming research posts will update our related Road Funding Index, and revisit discussions of Michigan’s overall Road Program performance.

Footnotes

1. Roughness is typically measured using the well-established International Roughness Index (IRI). However, some states report roughness on minor FAE routes using an alternative measure known as Present Serviceability Rating (PSR). ↩︎
2. A caveat to this table is that condition data was scored and ranked as a percentage of data reported. Several states did not report roughness condition data on a substantial percentage of their FAE network, including peer states of Wisconsin (9.8% unreported), Virginia (15.5% unreported) and Indiana (60.2% unreported). ↩︎
3. All states report roughness data on the NHS using the high-quality IRI measure. ↩︎
4. Michigan reports that the state’s NHS roads carry over 140 million miles of vehicle travel each day on average. The pavement roughness condition for about eight percent of this traffic was not reported. This is an unusually high percentage of unreported data, possibly reflecting the extent of the network under active construction during the reporting year. The figures given for Michigan and all states are as a percentage of ADT conditions reported. ↩︎

Additional data and methodology details will be made available upon request to epdennis@crcmich.org. CRC welcomes any and all feedback concerning this research as to provide the most comprehensive and meaningful assessment of comparative state road system conditions as is possible.