National Academies Press: OpenBook

Converting Paved Roads to Unpaved (2015)

Chapter: Chapter Two - Summary of the State of the Practice

« Previous: Chapter One - Introduction
Page 6
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 6
Page 7
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 7
Page 8
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 8
Page 9
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 9
Page 10
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 10
Page 11
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 11
Page 12
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 12
Page 13
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 13
Page 14
Suggested Citation:"Chapter Two - Summary of the State of the Practice ." National Academies of Sciences, Engineering, and Medicine. 2015. Converting Paved Roads to Unpaved. Washington, DC: The National Academies Press. doi: 10.17226/21935.
×
Page 14

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

7 aggregate loss, higher dust levels, and more frequent blading requirements (Skorseth and Selim 2000). Many of the con- verted roads identified in the survey and interviews carried out in this study had ADT of 21 to 100 vehicles, suggesting that many of the roads being converted probably should not have been paved or that road usage patterns have changed signifi- cantly since paving. The spectrum of options of surface types for low-volume roads ranges from gravel with no treatment to stabilized gravel to bituminous sealed bases to asphalt and concrete pavements (Figure 3). Each road surface type has its own merits and rep- resents one tool in the road management toolbox. Unpaved roads can be defined as those with a surface course of unbound aggregate (gravel) where no binder, such as tar, bitumen, cement, lime, or other chemical additive, is used. An unpaved road often requires blading at least once annually to maintain the road surface in a drivable and safe condition. Paved roads are defined as those with an asphalt concrete or portland cement concrete surface (Humphries 2012), or roads that possess any combination of asphalt binder and aggregate intended to pro- vide waterproofing, adhesion, structural strength, and frictional resistance (Shuler 2009). CONVERTING ROADS FROM PAVED TO UNPAVED Active versus Passive Conversion Many transportation agencies facing budget shortfalls and deteriorating paved roads are converting their paved roads to gravel (active conversion), whereas other agencies are allow- ing roads to deteriorate to unpaved conditions owing to a lack of funding for maintenance (passive conversion) (Figure 4) (Etter 2010; Taylor 2010). Active conversion is the process of converting a paved road to an unpaved road using equipment and personnel to recycle the old pavement into a pulverized material that can be used as a base for a new aggregate surfac- ing or as part of the new surface (Figure 5). Passive conversion of a road from paved to unpaved is the natural process of the paved road breaking down and deteriorating to an unpaved surface as a result of exposure to the elements and wear and tear from vehicle traffic. Based on survey and interview responses, active conversion is a far more common practice, however some local road agencies find that passive conver- sion occurs simply as a result of a lack of funding for properly maintaining roads. This chapter defines relevant terminology and identifies the state of the practice of converting roads from paved to unpaved, based on information gained from the literature review, survey of practitioners, and follow-up interviews. Information is pre- sented on how low-volume roads are defined in the context of road conversion projects, active versus passive conversion, factors to consider for conversion projects, road condition assessment tools, public reaction and outreach efforts by local road agencies, changes in traffic patterns and vehicle type on converted roads, changes in agency equipment and staffing to maintain unpaved roads, health and environmental impacts associated with unpaved roads, roadway safety, and economic considerations. The chapter ends with a summary of the state of the practice gleaned from survey responses. LOW-VOLUME ROADS There are more than 4.1 million mi of roadways in the United States (FHWA 2014). There is no uniform agreement on how many of these are low-volume roads. About 53% are unpaved and are maintained by local and state transportation depart- ments (Skorseth and Selim 2000; Anderson and Gesford 2007). A majority of these roads will remain unpaved because of continued low-volume traffic and economic considerations (Skorseth and Selim 2000; Anderson and Gesford 2007). Unpaved roads are nearly always considered low volume. Low-volume roads are defined by AASHTO as those with limited use—daily traffic of fewer than 400 vehicles (AASHTO 2001) and design speeds of less than 50 mph (Keller and Sherar 2003). The Manual on Uniform Traffic Control Devices (FHWA 2009) similarly defines a low-volume road as “lying outside of built-up areas of cities, towns, and communities, and it shall have a traffic volume of less than 400 AADT.” A Finnish study published in 2003 classified low-volume roads as those with AADT of no more than 250 vehicles, with threshold values used to define low vol- ume in case studies across Finland as AADT of from 100 to 350 vehicles (Mustonen et al. 2003). Many engineers use 150 to 200 vehicles per day, or equiv- alent heavy-weight traffic, as an unwritten guideline for defin- ing a low-volume road (Louwagie 2011). Gravel road surfaces are considered to be generally effective where AADT is less than 170 vehicles (Skorseth and Selim 2000). Roads with AADT greater than 170 vehicles have experienced significant chapter two SUMMARY OF THE STATE OF THE PRACTICE

8 Factors to Consider for Unpaving Factors to be taken into account when considering converting a road from paved to unpaved include the following (Mustonen et al. 2003; Sacramento Area Council of Governments 2008; Iowa Local Technical Assistance Program 2012): • Road condition: This dictates whether a deteriorated paved surface can be economically repaired to restore it to an acceptable condition or whether there is a need for complete rehabilitation or reconstruction, which may not be affordable. In the latter instance, conversion to gravel can be considered. • Safety: The deterioration of a paved road surface may be such that it may be safer to convert to a gravel sur- face either permanently or for an interim period until the road can be rehabilitated or reconstructed. • Number of residents along the road and the social and economic aspects of the road: The impacts of variable ride quality and dust on road users, residents, animals, produce, vehicle operating costs, and vehicle produc- tivity (possible reduced speed) when converting to an unpaved road all need to be considered. It is important that these be compared with the same impacts resulting from badly deteriorated paved roads. • Traffic volume and vehicle fleet distribution/type – AADT: Traffic counts must always be considered when converting paved roads to unpaved. Depending on traffic volume, seasonal distribution of the traffic, gravel quality, and average precipitation, gravel sur- faces can become difficult to maintain. – Presence of heavy and overweight vehicles: A high volume of heavy vehicles has a significant impact on the standard required for pavement maintenance and rehabilitation. Initial costs to repave or repair a road to an appropriate standard for these vehicles may be unaffordable for achieving an acceptable life cycle. Gravel roads can be much cheaper to repair when FIGURE 3 Spectrum of road surface types. FIGURE 4 Passive conversion, a local road that has been converted to gravel surfacing only when a section fails. (Photo courtesy of K. Skorseth.) FIGURE 5 Active conversion of a failing pavement by adding new gravel and recycling. (Photo courtesy of K. Skorseth.)

9 damaged, but the frequency of repair may be greater. The options will need to be compared. • Economics of road treatment options (life-cycle cost analysis): The costs of maintaining or reconstructing a paved road versus the cost of converting the road to unpaved and maintaining the gravel surface need to be accurately quantified. Cost data include materials, labor, construction, and maintenance. It is important that life- cycle costs, not only immediate costs, be considered for each alternative to determine accurately which strategy will be the most economical. • Land use, including but not limited to residential, com- mercial, agricultural, and industrial, of the area accessed by the road: Most users prefer paved roads. It is impor- tant to determine if a paved road is a necessity or simply desired. Some agricultural produce and manufactured goods are susceptible to damage on rough roads, whereas users such as motorcyclists and those with vehicles tow- ing travel trailers and boats may avoid unpaved roads, causing additional economic impacts. Future develop- ments that may result in an increase in AADT or the type of vehicle also could be considered in the decision to pave or unpave. • Maintenance capability: Specific equipment and skills are required for paved and unpaved road construction and maintenance. The availability and affordability of either contracted or in-house equipment or skill need to be assessed to compare the ability to maintain each sur- face type effectively. Dust and erosion control may be a significant factor and could be considered for unpaved surfaces. • Environmental issues: Air and water quality impacts from dust and erosion can affect human, plant, animal, and aquatic health and create a safety hazard to drivers. Products used to stabilize the road surface and reduce dust can also affect the adjacent environment if incor- rectly selected or applied. • Dust and erosion control: These issues may or may not be a significant factor, but it is essential that they be considered for all surfaces. • Availability and quality of suitable unpaved road–wearing coarse aggregate sources: The quality and properties of the aggregate have a significant impact on the surface condition and frequency of maintenance required on unpaved road surfaces. Appropriate unpaved road sur- facing aggregates are not offered by many commercial aggregate suppliers and can be expensive or difficult to obtain. This issue is more important than many managers recognize. • Public issues: Citizens want to know why a paved road will be converted to unpaved. They deserve informa- tion that supports the decisions of elected officials and managers. Economics should be explained clearly and accurately, with as little technical language as possible. • Network significance of the road: Primary routes that are frequently used by public transport (including school buses) or emergency vehicles or are priority snowplow routes generally are not recommended for conversion from paved to unpaved surfaces. Local roads serving lim- ited access to residences or businesses are better candi- dates. Some agencies have written or unwritten policies to provide access to paved roads whereby citizens have to travel no more than a few miles to reach a paved road. It is important that these policies be factored into the deci- sion process. ROAD CONDITION ASSESSMENT TOOLS Paved roads with surfaces in poor condition with obvious dis- tresses or safety issues often are prioritized for conversion. Ride quality [International Roughness Index (IRI) or Pavement Condition Index (PCI)] values are also often used as a trigger for considering conversions, whereas some counties use a road management program (RMP) index. Mustonen et al. (2003) suggest that roads with 30% of the surface area falling below an acceptable condition may be appropriate candidates for conversion. Many local road agencies have developed their own meth- ods for setting priorities for these decision metrics. For many assessment tools, the metrics can be weighted based on the importance to a road segment or to the overall road network. When combined, these factors can be used to develop agency- specific RMP policies or pavement condition indices, which in turn can be used to prioritize which roads will be maintained with their current surfacing or converted to an unpaved surface (Montpelier City Council 2009, 2010; Minnesota Department of Transportation 2010). However, RMP policies may have limitations. For one county surveyed, an issue with the RMP involved funding being allocated to higher priority roads on the road network, essentially eliminating funding for general main- tenance and reconstruction on local roads and minor improve- ments on neighborhood routes because the road priority level was below the determined threshold. Examples of the use of road condition assessment tools include the following. • Stutsman County, North Dakota, is an example of a small agency using a formal documented road prioritization system to rank roads for maintenance and repair. Factors considered in the prioritization system can be weighted based on the importance of the road segment to the over- all network of roads. The system aids in the decision- making process of weighing funding constraints against safety and liability on deteriorated paved roads that still cost substantial amounts of money to maintain, even in poor condition (Minnesota Department of Transporta- tion 2010). • The city of Montpelier, Vermont, uses a PCI to rate the roads within the municipality, with a rating of 0 indicat- ing a completely failed road and 100 an excellent road. PCI ratings from 1 to 13 are low enough to be considered

10 for conversion from paved to unpaved (Montpelier City Council 2009, 2010). • The Indiana Local Technical Assistance Program (LTAP) published a handbook in 2013 that provides guidelines for evaluating the state of paved and unpaved road surfaces and provides typical costs for various types of mainte- nance. Also included in the handbook are cost assess- ment comparisons for varying levels of maintenance on a gravel surface and varying conditions on an asphalt road surface with AADT of 100 vehicles over a 14-year period, to highlight the potential savings (or lack thereof) of converting to gravel. These cost assessments are fol- lowed by a detailed method of scaling the costs, with weighting of variables to determine which alternative is the most economical over a 14-year analysis period based on factors such as traffic volume, development, and public preference. The publication also points out the safety issues when converting to gravel, such as the possible changes of emergency response vehicle routes and subsequently increased response times (Indiana Local Technical Assistance Program 2013). • The Pavement Surface Evaluation and Rating (PASER) system (Walker et al. 2013) is a tool that can be used to assess road pavement condition quickly on a scale from 1 to 10. A rating of 1 or 2 indicates a poor to failed road surface in need of urgent maintenance. The ratings are associated with road condition categories and prescribed treatment options. The PASER system can be used for asphalt, concrete, brick and block, sealcoat, gravel, and unimproved roads and allows for comparison of road segment quality and the identification of roads requiring treatment. • Franklin County, Alabama, uses an asset management system with geographical information system (GIS) tools incorporated into a pavement management system, to make informed decisions about road maintenance and road conversions (D. Palmer, personal communication, May 14, 2015; see Franklin County, Alabama Case Example in Appendix D for more information). These tools are used to model the road system and prioritize roads for maintenance and upgrading. The system con- siders road surface condition, base condition, traffic volumes, number of residents served, segment classi- fication, repair costs, and other variables. Each road in the county is inspected every 2 years and given a rating from 1 to 100. These values are entered into the GIS system, which has a selection of relevant metrics (e.g., the rating, road classification, AADT) that are used to prioritize and rank road maintenance needs and allocate funds based on the level of service warranted by the road. The system is linked to a database of unit prices for a variety of materials and processes. The system can be used to create color-coded maps based on the input data and recommendations. These are used to quickly and visually communicate road conditions and mainte- nance costs and options to decision makers and the pub- lic, rather than requiring people to read through large budget documents. PUBLIC REACTION AND OUTREACH EFFORTS Much of the documented initial public reaction to road con- versions has been negative; however, responses from the sur- vey and follow-up interviews indicate that agencies that work with and communicate well with the public aid in acceptance. Based on survey and interview responses, it appears that if properly maintained, roads that have been converted generally are accepted by the public because of the improved driving surface and increased level of safety. However, the range of public reaction to road conversions varies greatly, with both the literature review and surveys indicating that some affected residents are more understanding and accepting than others and highlighting the importance of using appropriate termi- nology when communicating with the public. Examples highlighting the importance of public outreach include the following: • The word “unpaved” was perceived negatively by attend- ees of a public county board meeting in Freeborn County, Minnesota, because the term was associated with loss of service (Minnesota Local Technical Assistance Program 2012). • In Sequoyah County, Oklahoma, residents had difficulty accepting the change from asphalt pavement to a per- ceived lower level of service on the unpaved gravel road despite the poor condition of the asphalt road (Cameron 2010). One resident noted that although driving on the gravel road was not pleasant, conversions were under- standable given that the county had limited funds avail- able to keep the roads passable. A resident who lived next to a recently converted road said that the dust was bothersome but that the road condition was much better than the distressed paved road because the potholes had been removed in the process (Cameron 2010). • To address public relations in Indiana, the LTAP con- ducted seminars, titled “Back to the Stone Age,” about the conversion process and discussed measures taken to ameliorate residents’ concerns, such as developing a plan to manage dust on the unpaved road (Taylor 2010). • Some constituents believe they deserve a paved road regardless of the funding situation. In Mahnomen County, Minnesota, in a meeting with concerned citizens who lived on or near the road slated to be converted, citizens stated that regardless of cost, they believed it was their right to have the road reconstructed and paved. The resi- dents filed complaints with legislators and the Minnesota Department of Transportation (DOT) (MnDOT) object- ing to the road conversion project [Minnesota County Engineers Association (MCEA) Members Forum 2011]. For many other road conversion projects, public reaction has been negative, with residents reaching out to state

11 and local government officials to express concerns or prevent the conversions from taking place (Rajala 2010; Taylor 2010; Gillie 2013; Christensen 2013). • In Texas, the public reaction to planned road conversions by the Texas Department of Transportation (TxDOT) was negative, and the lack of communication between TxDOT and county officials was of primary concern. The point was made that TxDOT should have commu- nicated more effectively instead of simply announcing the conversion would occur (Batheja 2013). Concerns and questions raised included concern that converting the road to gravel would cause insurance rates to increase and property values to decrease, in addition to causing extra wear and tear on cars (Floyd 2013). Public opinion was sufficiently negative that in August 2013, TxDOT agreed to cease all conversions for a period of 60 days. By this time, two roads had been converted to gravel. TxDOT issued a letter announcing the end of its pro- gram of converting roads and requesting an additional $402 million for the remainder of the 2014 fiscal year to fund “critical safety projects” and tackle roads compro- mised by the oil boom (Batheja 2014). • In Brown County, Indiana, residents noted that they do not miss the bad paved road because the converted road is well maintained and has a smooth driving surface (The Indy Channel 2012). • A resident who lives along Lake Montcalm Road in Montcalm County, Michigan, noted that the converted road was smoother than it was when paved but expressed concern about how it would be maintained in the winter (Martin 2009). • In Baldwin County, Alabama, a letter was sent to resi- dents living along a road slated to be converted stating that if the road were left as it was, the county would not be able to plow snow from the road (MCEA Members Forum 2011). The lack of comments from residents regarding the road conversion was considered to be pub- lic acceptance of the situation. • In Sonoma County, California, residents understood the lack of funds to repave the road but were upset that the county did not notify them that Sonoma Mountain Road was being converted (Brown 2010). In hindsight, the county acknowledged that residents should have been notified of the change (Brown 2010). An example of a successful outreach effort by the city of Montpelier, Vermont, is a letter sent to road users to inform them of an intended road conversion (see Appendix F). In addition to the letter, a public hearing was held before and after completion of the road conversion, to address concerns such as dust control (T. McArdle, personal communication, April 24, 2015). At the hearing held after the road conver- sion, people (including motorcyclists) were supportive of the new unpaved road. The public outreach efforts worked well in this situation and were considered successful. The city of Montpelier acknowledged that this was a good lesson for the road agency to consider in future conversion projects and that involving the public early in the process about the real- ity of the current paved road condition versus the expected unpaved road condition was important. Changes in Traffic Patterns and Vehicle Type Modern agricultural equipment (i.e., tractors, combines, farm trucks) have greatly increased in size and carrying capacity, along with greater crop yields, creating increased mainte- nance issues on paved and unpaved rural roads (Anderson 2011), with accelerated degradation of low-volume roads (Figure 6). Multiaxle semis, concrete haulers, large-load log trucks, and rising traffic volume can be equally destructive (Etter 2010; Taylor 2010) (Figure 7). In some areas of the country where oil drilling and extraction have increased, such as North Dakota, Texas, and Pennsylvania, significant dam- age to roads from oil field traffic has occurred (Floyd 2013). Many of these rural paved roads have passed the end of their design life (Anderson 2011). For example, in South Dakota many 30-year-old pavements are still in place although they had projected life-cycles of 20 or 25 years (Landers 2011). Examples of how changes in traffic patterns and vehi- cle type influence decisions to convert roads include the following: • In Pennsylvania, two counties have used conversions from paved to unpaved as traffic-calming measures. Tinicum Township in Bucks County and Marlborough Township in Chester County have both converted paved roads to gravel in an attempt to deter and slow traffic. However, no data could be found supporting that this method of traffic calming was effective or resulted in a change in traffic patterns. • In Michigan, a resident of Montcalm County noted a reduction in traffic speeds along Lake Montcalm Road, which was converted to gravel in 2009 (Martin 2009). • Concerns have been expressed by business owners and residents in Stutsman County, North Dakota, about a potential reduction in customer and tourist traffic on a local road owing to portions of the road being converted from paved to unpaved (Etter 2010). Views expressed in a letter to the editor of the Jamestown Sun newspaper suggested that vehicle traffic would actually increase on the converted road as a result of the construction of a new industrial park, which is accessed by the road (Mosolf 2010). However, no documentation was found showing that the road conversion resulted in a change in traffic patterns or a change in the amount or type of traffic. • Tooele County, Utah, converted 13 mi of a connector road accessing a water skiing lake and resort. The direc- tor of the Tooele County Road Department noted that although there is a different, paved route to the recreation site that is only slightly longer, traffic remains more or less the same on the road that was converted. The owner

12 of the resort noted that the only time users choose to take the longer, paved route is when they are towing a trailer (Gillie 2014). Recreationists have asked that the road be repaved, in part because of the possibility of loose rocks damaging their boats. Changes in Agency Equipment and Staffing Converting roads may require agencies to purchase or hire additional equipment to do the conversion or maintain the unpaved road. Numerous interviewees indicated that standard reclaiming or recycling equipment was used for conversions in their respective jurisdictions. However, few responding agencies who indicated that this type of equipment was used to convert roads from paved to unpaved actually purchased or owned it; many rented the machines. Examples from the survey include the following: • In Vermillion County, Indiana, some agency changes were required when a 16-mi section of paved road was converted to gravel in 2013. The county has 193 mi of paved road and more than 189 mi of gravel road. To handle the increasing number of unpaved road miles, highway maintenance crews are being retrained on how to maintain gravel roads effectively (Greninger 2012). • In 2010, Stutsman County, North Dakota, purchased a reclaiming machine ($400,000) for use in part to con- vert numerous roads in the county (Etter 2010). • The public works department in Montpelier, Vermont, added a new road grader to its equipment fleet after converting two roads to gravel in part to keep up with required maintenance (Montpelier City Council 2010). Health and Environmental Impacts A significant environmental impact from gravel roads is dust, which has been associated with health issues, air pollution, (a) (b) (c) FIGURE 6 A 1950s era farm truck (a). Many local roads that were designed to carry this type of vehicle carry today’s larger agricultural equipment and trucks (b) and (c). (Photos courtesy of K. Skorseth.) FIGURE 7 A township road failing because it carries heavy loads for which it was not designed. (Photo courtesy of K. Skorseth.)

13 and crop damage. Dust can be mitigated by refining gravel specifications or by using an appropriate dust suppressant. However, potential environmental impacts related to the use of chemical dust suppressant and stabilizers during and after the conversion process must be considered. Examples of concerns identified in the literature and raised during the survey include the following: • A resident of Midland County, Michigan, suggested that dust control palliatives and dust from the pulverized road affected the fertility of his land (Warrick 2013). • In Washington County, Oregon, a nursery owner tracked the losses associated with his fields located near gravel roads. The impact of road dust on crop production was roughly $3,000 per year for every 100 ft of gravel front- age and rendered some portions of his crop nearest to the road unsellable (Clemmons and Saager 2011). • In Napa County, California, the Department of Public Works received an inquiry from the Department of Fish and Wildlife on behalf of a constituent concerned that pollution in a nearby creek was associated with a recent road conversion project (S. Stangland, personal commu- nication, May 6, 2015). The creek and converted road were investigated, but no impacts were found. • In Montpelier, Vermont, residents expressed concern that the use of calcium chloride as a dust suppressant could affect drinking water wells. Previous studies completed by the Vermont DOT found that calcium chloride can permeate the gravel but that it stays in the soil. Based on this research, the city determined there would be no impact to the well water (Montpelier City Council 2010). • In Sonoma County, California, a resident discovered the road in front of his house had been converted while he was out of town on vacation. The resident was concerned about the impacts the dust would have on his asthma and implied that recreational use of the road may need to be reduced (Brown 2010). • In Midland County, Michigan, residents of Shaffer Road experienced health problems following pulverization of the road in 2010. Eye, nose, and throat irritation was caused by what was defined as “toxic dust” from the pul- verized road surface. Midland County did not have the funding required to test the dust for toxicity. However, similar concerns were raised when nearby Muskegon County pulverized a road. One township within the county paid for an independent analysis of the dust by a private laboratory, which found “six probable carcino- gens and eight substances classified by the U.S. EPA as priority pollutants when found in drinking water” (Midland Daily News 2011). Recommendations from the manufacturer of the pulverizer indicated that sealing a road after it is pulverized is important to reduce dust. Shaffer Road was not sealed or resurfaced because of limited funds. To manage the dust issue, residents now pay for extra calcium chloride applications to reduce dust, have purchased home air purification systems, and avoid walking and biking on the road to minimize their exposure to the dust (Warrick 2013). • One instance was found for which material used to seal a road was classified as a hazardous substance but rated as safe for use on roads. The product was used because it was donated to the county by Utah Power and Light (Christensen 2013). No additional information on this product or impacts was provided. ROAD SAFETY A primary reason for converting a road from paved to unpaved, as indicated in the literature and from the survey and inter- views, is safety concerns (Figure 8). Many agencies and practi- tioners contend that a gravel road can be maintained to a higher safety standard than a deteriorated paved road and often at less cost. However, gravel roads can still pose a variety of safety concerns, with poorly maintained gravel roads often being dusty and having washboarding, loose gravel, and potholes, which lead to unsafe and uncomfortable driving conditions. Anecdotal evidence suggests there may be an increased rate of crashes on roads that have been converted. However, survey responses from local road agencies indicated that no FIGURE 8 Examples of road safety effects caused by failing asphalt roads. The failures force traffic to travel outside of the lane and disrupt traffic movement. (Photos courtesy of K. Skorseth.)

14 documented increase in vehicle crashes has been found on any of the converted roads or road segments; interviewees indicated that the improved unpaved driving surface reduced the occurrence of crashes. According to the Sacramento Area Council of Governments (2008), converting poor-condition paved roads to unpaved roads can help prevent accidents because of decreased driving speeds. Limited published data are available on crashes on local roads, specifically on low-volume roads that have been converted from paved to unpaved. The county engineer in Freeborn County, Minnesota, stated, “There is a need for better and more readily available crash data, specifically on local roads, as it relates to improving rural road safety.” Historically, local roads have a higher rate of fatalities per million miles traveled than primary roads, but minimal infor- mation has been collected about crash rates and fatalities on roads that have undergone a conversion (Kuennen 2010). To address these issues, ongoing NCHRP Synthesis project 46-07: State Practices for Local Road Safety is being done to identify state programs used to address local agency road safety, par- ticularly on low-volume roads. This report is scheduled to be available in early 2016. The literature review and survey identified mixed responses on how road conversions affected safety, including the following: • In Sitka, Alaska, a road was converted because of safety concerns. Motorists were swerving to avoid potholes and had difficulty navigating a hairpin turn. Anecdotal evidence suggested that safety improved after the con- version (Woolsey 2014). • In Montcalm County, Michigan, a 15-mi section of road was converted in part because of accidents related to the surface condition of the paved road. The unpaved road has been maintained appropriately, and the county has observed no documented increase in vehicle crashes. • In Tooele County, Utah, many residents raised concerns regarding decreased visibility resulting from dust after a 13-mi section of paved road was converted to unpaved. However, the road department treated the road with magnesium chloride as a dust abatement procedure and continues to assert that the road can be maintained to a higher safety standard as a gravel road rather than a pothole-filled paved road (Christensen 2013). The mayor and local residents suggested vehicle accidents rates decreased when the road was paved and that isolated rollover accidents occurred on the unpaved road because people “did not know how to drive on the gravel surface” (Christensen 2013). • An accident occurred in 2010 in Rogers County, Okla- homa, in which a driver lost control of his vehicle, result- ing in a rollover. The road had been converted temporarily to gravel, and although state troopers cited high speed as the cause of the accident, they noted that gravel could exacerbate the risks of speeding (Cameron 2010). • Anecdotal evidence from residents living on Sonoma Mountain Road in California suggests that vehicle acci- dents can be attributed to drivers losing control on the new unpaved surface (Brown 2011). ECONOMIC CONSIDERATIONS—COST OF CONVERTING VERSUS REPAVING The 2010 Wall Street Journal article “Roads to Ruin: Towns Rip Up the Pavement” highlighted the economic strain many counties face when trying to maintain paved roads in rural areas (Etter 2010). A recent study found that the state of Iowa would need to increase road funding by $220 million annually just to maintain the current road network (Anderson 2011). Similar funding shortfalls for local road maintenance budgets are occurring across the country (Canfield 2009; Taylor 2010; Landers 2011). Cold-weather states in particular have high maintenance costs resulting from the repair of damage caused by freeze-thaw cycles but little available funding because of essential winter maintenance operations (Canfield 2009). Coupled with declining budgets, agencies have seen raw material prices increase. Costs for gasoline, diesel, and asphalt binder, all petroleum-based products, are tied to fluctuating oil prices (Taylor 2010). However, fuel taxes, which are a primary source of funding for road maintenance, have remained constant in this time period. Improved fuel consumption technologies have further reduced this source of income. The recent economic downturn has made governments reluctant to increase other taxes and has resulted in people driving less. In 2015, Iowa enacted a 10-cent-per-gallon increase in the state’s fuel tax for the first time since 1988 in an effort to cover a $200 million road construction and main- tenance deficit (Anderson 2011; Murphy 2015). Minnesota attempted to increase county maintenance budgets by raising the state’s gas tax by 8.5 cents in 2008, but county officials warned it would not be enough to keep up with rising mainte- nance and paving costs (Louwagie 2011). Examples of economic considerations cited in the litera- ture and surveys follow. Michigan • According to a county road commissioner, Michigan is ranked 50th in per capita spending on road maintenance in the country (Canfield 2009; Rajala 2010). In Mont- calm County, patching of a primary road cost more than $39,000 in 2008 and 2009. However, it cost only $7,300 for the road to be converted to gravel. • Road conversion projects in Benzie County, Michigan, have resulted in significant savings in maintenance costs by eliminating the need for two-person patch crews working 1 to 2 days per month and replacing that process

15 with annual brine application (Minnesota Department of Transportation 2010). • The Branch County Road Commission in Michigan was spending nearly $2,000 per week making repairs to a road. A 1-mi stretch of the road was converted to gravel at a cost of $6,370 (Reid 2014). • In Emmet County, Michigan, repairing just more than 3 mi of a severely potholed road cost $20,000 to $30,000 per year. After the road was converted to gravel, main- tenance costs were reduced by about $10,000 annually, with an initial (up-front) cost of $12,000 for pulverizing the paved road (Keller 2010). Midwest • In 2013, the Indiana LTAP published Assessment Pro- cedures for Paved and Gravel Roads, a handbook that addresses some of the issues facing underfunded coun- ties in Indiana. Cost estimates from the report place the cost of recycling a paved asphalt road, stabilization of the base, and addition of a new gravel surface at $42,000 per mile. Alternatively, the cost to maintain the asphalt with similar treatments to the subsurface and a new asphalt overlay was estimated at $112,000. • In Hancock County, Minnesota, estimates for initial con- struction and 5 years of maintenance suggested a total cost savings of $3,000 per mile (Minnesota Department of Transportation 2010). • In North Dakota, Stutsman County expenses outweigh income, and the county has revenue to maintain only 48 of the 233 mi of paved road. Cost estimates for repav- ing a deteriorated road segment were around $75,000 per mile, whereas projected costs for maintaining the road as gravel were $2,600 per mile (Arndt 2010; Etter 2010). The county estimated it would cost $32,000 per mile in maintenance costs over the 20-year life-cycle for a low-volume paved road, whereas that same 20-year maintenance cost would drop to $4,300 per mile for a reclaimed road and lower still to $1,700 per mile for a gravel road (Landers 2011). • In Allamakee County, Iowa, the cost estimate for sur- facing roads was about $100,000 per mile, compared with only $5,000 per mile to remove the pavement and add new gravel (Louwagie 2011). West Coast • In Union County, Oregon, about 5% of the 150 mi of paved roadway has been converted to unpaved gravel roads because it was cheaper than trying to maintain the roads as paved (Cooper 2008). • In Lake County, California, paved roads were recycled with a pulverizer followed by an enzyme application (Brown 2010). The county won an award in 2009 from the California Chip Seal Association for Innovative Proj- ect of the Year for the resurfacing of two of the converted roads. Overall, the county saved about $190,000 with the technique used instead of a traditional pavement overlay (Larson 2010). East Coast • High asphalt and transportation costs were motivation for Cranberry Isles, Maine, to consider converting three of its major roads to gravel (Rajala 2010). Repaving was estimated to cost the town (population 118) nearly $500,000, whereas converting to gravel cost $58,000, with most labor performed by public works personnel (Montpelier City Council 2010).

Next: Chapter Three - Summary of Survey Results »
Converting Paved Roads to Unpaved Get This Book
×
MyNAP members save 10% online.
Login or Register to save!
Download Free PDF

TRB’s National Cooperative Highway Research Program (NCHRP) Synthesis 485: Converting Paved Roads to Unpaved explores how common and under what conditions paved roads are converted to unpaved.

NCHRP Synthesis 485 found that the practice of converting paved roads to unpaved is relatively widespread; recent road conversion projects were identified in 27 states. These are primarily rural, low-volume roads that were paved when asphalt and construction prices were low. Those asphalt roads have now aged well beyond their design service life, are rapidly deteriorating, and are both difficult and expensive to maintain. Instead, many local road agencies are converting these deteriorated paved roads to unpaved as a more sustainable solution.

According to the report, local road agencies have experienced positive outcomes by converting roads. Many local road agencies reported cost savings after converting, compared with the costs of continuing maintenance of the deteriorating paved road, or repaving. One key to successful conversion is early involvement of the public in the planning process. Other techniques that can be used to improve the overall results of a project include treating or stabilizing granular surfaces to control dust, limiting the rate of aggregate loss, and reducing motor grader/blade maintenance frequency. Stabilization procedures can also improve safety, increase public acceptance, and reduce life-cycle costs and environmental impacts after a conversion has taken place.

  1. ×

    Welcome to OpenBook!

    You're looking at OpenBook, NAP.edu's online reading room since 1999. Based on feedback from you, our users, we've made some improvements that make it easier than ever to read thousands of publications on our website.

    Do you want to take a quick tour of the OpenBook's features?

    No Thanks Take a Tour »
  2. ×

    Show this book's table of contents, where you can jump to any chapter by name.

    « Back Next »
  3. ×

    ...or use these buttons to go back to the previous chapter or skip to the next one.

    « Back Next »
  4. ×

    Jump up to the previous page or down to the next one. Also, you can type in a page number and press Enter to go directly to that page in the book.

    « Back Next »
  5. ×

    To search the entire text of this book, type in your search term here and press Enter.

    « Back Next »
  6. ×

    Share a link to this book page on your preferred social network or via email.

    « Back Next »
  7. ×

    View our suggested citation for this chapter.

    « Back Next »
  8. ×

    Ready to take your reading offline? Click here to buy this book in print or download it as a free PDF, if available.

    « Back Next »
Stay Connected!