Road Maintenance Costs – Unpaved vs Paved Roads

Unpaved vs Paved Roads: Understanding the Hidden Road Maintenance Costs That Drain Your Budget

In Road & Surface Management, Roads, Unpaved Roads by Bob Vitale

How far in the future do you plan your road maintenance costs? 

Many county officials only make it through the next year, responding to needs as they arise. They track annual road maintenance costs using those numbers to make decisions going forward. 

But even with such a short-sighted view, it’s easy to see the challenges ahead: rising maintenance costs, stagnating tax revenue, more wear and tear on roads from more vehicles (or bigger, heavier vehicles). 

As roads near the end of their lives, those county and township officials who are looking a few years ahead feel the pressure of the large, one-off costs of reconstruction. No amount of planning can ease the challenge that those significant costs can pose to a local road maintenance agency. 

One township in Minnesota saw these headaches coming 20 years early. The first decade of the century saw rapid population growth, and with it a lot of new paved roads. While these roads are relatively affordable to maintain at first, the township recognized that they would all age at the same rate, meaning by 2030 they will all need a new bituminous overlay. 

So how can a township or county respond to these challenges? 

The first step is to get a realistic picture of the road maintenance costs you’re facing. 

In a soon-coming second article, part two of this series on unpaved road maintenance costs, we’ll address how to extend the lifecycle and performance of your unpaved roads, including addressing a new idea that has emerged from our research and experience at Midwest. 

This conversation is particularly relevant to: 

  • Counties or townships that have paved roads that are at the point of needing to be rebuilt – and therefore are facing decisions about next steps for those roads
  • Counties or townships with gravel roads that are experiencing an increase in traffic volume, and are debating upgrading to paved roads
  • Local officials who aren’t sure how to justify the extra cost of dust control in their gravel road maintenance budget

The Many Types of Road Maintenance Costs

Maintenance costs are just one part of the expense of keeping up roads. A 2012 study of Iowa county roads determined that there are two broad categories of costs. The first is carrying costs. These include: 

  • Operating costs (such as snow and ice removal) 
  • Maintenance costs (grading for gravel roads, patching and striping for paved roads) 
  • Extensions (layouts made to partially restore, seal coats, adding aggregate, etc.)
  • Renewal expenses (restore to as-constructed state – full rock overlay, reconstruction of design base, repaving)

The second category is upgrade costs. These occur when the volume of traffic using the road (physical design level – PDL) exceeds the level of traffic that the road is designed to safely carry (the traffic design level – TDL). 

The difference between renewal and upgrade costs are that renewal efforts are designed to get the road back to the shape it’s in today, while upgrade efforts are geared towards taking the road to the next traffic design level – capable of withstanding the new level of traffic volume the road is experiencing. 

The problem with upgrade costs is that they can create a downward spiral, something we at Midwest refer to as “the toilet bowl effect.” This is because upgrade costs consume funding that could have been used for carrying costs – which potentially leads to a decline in overall road conditions. 

As a result, both future carrying costs and upgrade costs are higher, creating a cascading budgetary challenge. 

Comparing Unpaved and Paved Road Costs

With the above context in place, we can now start to break down the differences in costs between paved and unpaved roads. 

(As a caveat, it’s important to realize that road maintenance costs vary significantly from place to place; even performing the same service on roads just a few miles apart can cost different amounts. This is due to a large number of factors, ranging from local geography and climate to material availability. 

Also, sources differ on exactly what activities are needed when, so your best bet is to work with a consultant who can evaluate your specific roads to determine the best mix of management activities. Midwest has been doing this for years as part of our comprehensive dust control and road stabilization program we offer to our client-partners.) 

Generally speaking, gravel roads will actually cost more to maintain than paved roads. 

One Minnesota county’s road maintenance figures demonstrate this: from 2005-2009, they spent $43,411.23 to maintain 23 miles of gravel road. In the same time, they spent $27,293.13 to maintain 2,028.6 miles of paved road. This is a difference of $1,887.44 per mile of gravel road versus $13.45 per mile of paved road. 

In a document from the U.S. Environmental Protection Agency on when to pave a gravel road, they mock up some maintenance numbers for the sake of demonstration. In their numbers, the gravel road maintenance costs are just over four times the paved road maintenance costs.  

The Upper Great Plains Transportation Institute provides a calculator to help make decisions about choosing a surface material for roads. Keeping all of their standard assumptions in place, comparing road maintenance costs between a paved and gravel road over the first three years reveals the following: 

Year 1:$7,400$0
Year 2:$7,400$1,500
Year 3:$9,400$1,500

Even in the Iowa study referenced earlier, where maintenance costs were found to be higher for paved roads than for gravel ones, the “needed” dollar amount (higher than the actual amount spent) was only a $1,200 difference per mile. 

One of the main reasons for this difference in road maintenance costs between paved and gravel roads is that the maintenance frequency required for an unpaved road is about four times higher than it is for paved roads. In fact, whereas a paved road can last for about 20-25 years before needing major reconstruction, gravel roads can deteriorate from excellent to failed condition in less than a year. 

All of this being said, we’ve only been discussing maintenance costs in the pure sense. Referring back to the Iowa study, the extend/renew expense categories involve reconstruction work. Things like bituminous overlay, seal coats, repaving, re-graveling. 

Building in these other occasional, but expensive, costs reveal the following in our various sources cited above:

  • Iowa study: the “needed” cost per mile for all categories of expenses together came to $4,661 per mile for gravel roads but $19,983 per mile for paved roads. 
  • Baldwin Township, Minnesota: between 2010 and 2013, costs per mile for paved roads ranged from between $62,370 to $138,951.71 for reclaim/overlay activities to $389,554.69 for complete reconstruction.  
  • The EPA document on paving gravel roads: in the hypothetical example provided, total expenses for upkeep of a mile of paved road over six years was $24,833, compared to $18,065 for a mile of gravel road ($4,138.83 per mile per year, compared to $3,010.83 per mile per year).
  • study of nine towns in New York: the study found that none of these towns had formal, multi-year plans for road management. At the time of the study, these towns had budgeted anywhere from $4,429 to $10,440 per mile for paved road management. Yet estimated costs ranged from $2,040 to $52,952 per mile, depending on the town. Some towns had budgeted more than enough, but others had significant shortfall: the town facing the largest cost per mile had only budgeted for 20% of what they ended up needing. 

So when all carrying costs are examined, higher classes of roads (e.g., paved roads) cost more to sustain than lower classes (e.g., gravel). But how do upgrade costs affect this? 

The Impact of Upgrade Costs

Remember the concept of physical design level (PDL) versus traffic design level (TDL) from earlier in this article? PDL is the actual status of the road, while TDL is the safe design level for which the road needs to be at given the amount of traffic it has. 

Upgrade costs kick in when the TDL is two levels or more higher than the PDL. How is this estimated? 

The Iowa study breaks down roads into 15 design levels, around four types of surface material (earth, granular [gravel], hard surface [chip seal] and pavement). The different design levels within each surface material category are broken down by road width. Each one of those is then matched up to an allowable amount of daily traffic. 

For instance, the two types of earth roads can carry up to 11 vehicles per day. The three different widths of granular road, altogether, carry anywhere from 12 to 125 vehicles per day. And so on. 

The researchers then created a chart with the PDL levels on the axis and TDL levels on the axis. They then mapped out every mile of road based on where it fell on both PDL and TDL levels. This allowed them to determine, for every mile of road, whether or not the PDL and TDL levels matched. Their results are in the following chart: 

Design Level DifferenceMilesPercent

Every mile of road from P<<T to P<<<<T (defined as where PDL is two to four levels lower than TDL) is in need of upgrade, but to varying levels of urgency. 

The researchers then overlayed the estimated cost to upgrade each of these miles of road to the needed level. As an example, 7,434.669 miles of “G1” (narrowest granular roads) needed to be upgraded to “G3” (widest granular roads). The total cost to do this: $1,541,200,000, or $207,299.07 per mile. 

Upgrading miles from PDL levels G1 and G2 to the TDL hard surface level (HS) would take $589,000 per mile and $554,000 per mile, respectively. 

Upgrading all of the most urgent roads to the necessary level would cost an astronomical $1,038,270 per mile

If following any of this gets confusing, we can summarize the last two sections this way: 

  • Preventative maintenance is cheaper than reconstruction. (Even though most townships and counties let preventative practices slide to try to save money in the short term.)
  • Upgrading a lower-class design road to a higher-class design to keep up with increased traffic volume will often cost hundreds of thousands of dollars per mile, or more. 

Needless to say, minimizing reconstruction and upgrade costs should be a priority in any road management plan. But given the financing challenges discussed throughout this article (including the tendency to shy away from spending money until a problem reaches “emergency” status), this is impossible with a conventional approach. 

For years, we’ve been keeping our eyes on road stabilization trends at Midwest. Our solution helps road managers break the downward pressure by designing roads that spread out maintenance costs, reduce reconstruction and carry more traffic.    

The Compounding Negative Cost Cycle

The researchers in the Iowa study found that the computed annual need for keeping up with road management expenses was $814 million per year (2011). However, actual expenditures were close to $690 million, meaning that over $120 million that needed to be spent on road management, wasn’t. As time goes on, this issue will only compound the problem, creating bigger funding gaps while roads continue to degrade. 

To make matters worse, road upkeep costs had been increasing by at least 6% per year for the decade leading up to the study. Meaning revenue sources also needed to rise by 6% per year just to keep up current levels. 

Because of these funding challenges, road managers are willing to let their roads’ physical design level drop below the traffic design level to an extent, but then have to face the costs of emergency road work if the level drops too low.  

The study authors conclude that there are only two options: seek more revenues (from local taxes or other means) or downgrade the whole system to more closely match the current budget. Both of these options are perceived negatively by communities. No one wants to pay more or get what they perceive to be less than what they currently do. 

How do you as a county official, road manager or budget planner cope with this challenge? 

We’ll address the two vital steps you can take to expand your maintenance dollars in the next article in this series. We’ll also fill you in on some of Midwest’s most up-to-date findings and ideas that have emerged as we’ve watched current trends gathering force in the industry. Keep an eye out for that article. 

Or, if you’d rather not wait, you can learn more about Midwest’s road stabilization program and how we can help you reduce road maintenance costs and extend the lifecycle and performance of your road.

Bob is founder and CEO of Midwest Industrial Supply.