A Step-By-Step Guide to Pavement Management

By Matt Indihar, Sr Project Manager and Matt Henderson, Graduate Engineer, WSB

Pavement management plans are crucial for cities to properly oversee their networks of pavement. These plans help decision makers maximize their limited budgets by implementing the most cost-effective maintenance solutions on every segment of their roads, parking lots, and trails. A good pavement management plan helps decide which roads should receive maintenance, when they should receive it, and what kind of maintenance would be best. Additionally, a pavement management plan must be frequently updated to accurately capture pavement conditions and needs.

It can be complicated deciding how to allocate funds in a network of roads. Fortunately, there are analytical and scientific ways to help cities decide on the best way to use their street maintenance resources. While the process of creating a pavement management plan can seem overwhelming at first, it can be broken down into six steps.

  1. Assess Inventory

The first step in creating a pavement management plan is to take inventory of all the roads that are to be included in the plan. This usually results in an updated map of all paved streets. Roads can be broken up into numbered segments so each section of pavement can be identified. Taking inventory can also include gathering maintenance records from recent pavement maintenance.

2. Pavement Inspection

Next, gather raw data from the pavement segments in the inventory. To understand the condition of each segment, the present pavement distresses are noted. Walking the streets and visually documenting distresses is one of the most detailed methods of capturing the data. An inspector can provide notes relating to unique distresses, maintenance, and other factors that cannot be captured by simply driving the road.

3. Condition Assessment

Once the raw data is recorded, the condition of a pavement section can be quantified using a single number such as a Pavement Condition Index (PCI) or Overall Condition Index (OCI) value. These numbers are calculated from the amount, type, and severity of the distresses surveyed. Having a segment represented by a single number makes it easier to compare against other segments. An average value condition index of the entire pavement network can be calculated to set budgets and track trends in the city’s pavement.

4. Condition Forecasting

Most pavements in a specific area exhibit a common pattern as they age. A standard degradation curve or a custom curve based on historical pavement maintenance tracking can be used to predict the condition of a segment in the future. This is important because pavement degradation is not constant. Knowing when a segment is about to enter a period of steep decline in condition is useful when deciding how to allocate maintenance resources and dollars.

5. Scenario Modeling

Using the current condition information and future condition information, a model can be created to analyze the future of a pavement network. Inputs such as budget, priority segments, preferred maintenance techniques, and construction costs are all variables that can be analyzed as models are created. These factors are dependent on discussions with the city to maximize the pavement conditions and align with a preferred strategy.

6. Capital Improvement Planning

The condition analysis allows cities to create a plan that optimizes pavement condition. Results usually include a list of road maintenance and construction projects that should be completed in each of the upcoming years. Furthermore, letting a computer optimize spending removes the guess work and ensures travelers are getting access to the highest quality roads possible. City officials can use the work plan to request work from contractors and notify residents of future projects.

While the six fundamental steps of pavement management are outlined above, every city has something that makes them unique. WSB has the technology and expertise to help tailor a pavement management plan for your community. We would be happy to discuss how we can help meet your pavement needs.

Matt Indihar is a Project Manager in WSB’s Construction and Design-Build Service Group with eight years of industry experience in construction and project development. Prior to
WSB, Matt worked at MnDOT’s District 3 where he served as a Graduated Engineer, Senior Engineer, and Resident Construction Engineer.

mindihar@wsbeng.com | 218.341.3614

Matt Henderson has experience performing construction inspection, contract administration, project management, and material testing on a variety of transportation projects. Prior to WSB, Matthew worked as a Planner and Assistant Project Manager for MnDOT in District 7 where he developed an expertise for coordination and communication with MnDOT and stakeholders.

mhenderson@wsbeng.com | 612.759.7218

Pavement

How pavement management is like owning and caring for a backyard deck

A Q&A with Bart Fischer, Senior Public Administrator and Mike Rief, Sr. Vice President of Construction Services.

With summer fast approaching it’s comforting to know that we’re free of icy road conditions for the next several months.  As I drove over a recent pothole and began noticing the sand and salt being swept off the roads in my community, I wanted to learn more about pavement management and its impact on city budgets and plans. I sat down with Mike Rief, WSB’s Sr. Vice President of Construction Services to better understand the importance of pavement management in our communities.

BF: Why is pavement management so important for communities?

MR: It all comes down to planning and budgeting. The predictability that a pavement management plan brings a community is the biggest benefit. If a pavement management plan exists, minor improvements and maintenance can potentially double the lifespan of a roadway.  Without any maintenance or improvements, a typical road will last about 20 years. Instead, with a pavement management plan, a community could extend that lifespan to about 40 years, maximizing their investment.

BF: That’s interesting. What exactly does a pavement management plan entail?

MR: I’ve found that comparing pavement to caring for a backyard deck has a lot of impact. We start by building a deck – similar to how we start building a road.  We form the foundation, wood for the deck and pavement for the road.

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BF: We love our outdoor spaces in Minnesota! This is a great comparison. So, there is a preventative maintenance component after the foundation is formed?

MR: Exactly. Once the foundation is formed, we perform preventative maintenance.  In the case of a deck, we stain and seal it. For pavement, we seal the pavement cracks and perform surface treatments.

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BF: What happens if a board rots out? How would you compare that in the pavement scenario?

MR: I like to call this the preservation stage of the pavement management plan. The best comparison to replacing a rotting board would be performing a mill and overlay on the road. A mill and overlay is a type of street maintenance that requires the removal of the top 2” of a street and the addition of a new layer of bituminous pavement in it’s place.

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BF: When does it make sense to do a full road reconstruction?

MR: Yes, the reconstruction phase of the process is inevitable, but can be extended through preventative maintenance and preservation. Eventually, we’ve repaired the deck so many times and it makes sense to stop investing more dollars into it.  At some point, reconstruction is necessary, but through pavement management, it’s decades out and has been budgeted for.

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BF: It really makes a lot of sense when you explain it in that way. Any other benefits of pavement management?

MR: I mentioned it above, but predictability is invaluable. There are huge capital investment benefits to implementing a pavement management plan.  It helps with budgeting, planning for development and growth and also can increase property values. I recommend any community, regardless of size, consider pavement management in the future.

Bart Fischer has over two decades of experience in public administration. Throughout his tenure, he’s worked in five Minnesota communities as the city or assistant city administrator.  Bart joined our firm in 2019 as a senior public administrator and focuses on lending his public service expertise to our clients.

bfischer@wsbeng.com | 651.485.1839

Mike Rief leads WSB’s Construction Services team. He has nearly 30 years of experience in civil engineering, with an emphasis on pavement and materials, pavement management, quality management, project management, design, risk assessment, project controls, contract administration, construction, and preventative maintenance. Throughout his tenure, he’s managed several complex, high-profile projects across Minnesota.

mrief@wsbeng.com | 612.518.8329

Make the most of your pavement

By Sheue Torng Lee, Graduate Engineer, WSB

As a city leader you are responsible for many things; managing budgets, people, community needs, city assets, and the list goes on. What if there were a system in place for managing one of your largest assets, the city streets?

A pavement management program provides a systematic method of inspecting and rating the pavement condition of your roads; including the analysis of various maintenance and rehabilitation strategies. As part of the program, we use pavement forensics to identify the pavement structure and condition underneath the visible surface of the pavement. We look at the depths and condition of the pavement layers, signs of bonding or de-bonding, and distresses that may not be visible from the surface. Data collected from the pavement cores during forensics, provides a better understanding of the roadway sections and allows us to determine cost-effective and appropriate pavement rehabilitation techniques. The program is designed to help you get the most out of your available resources.

The collected data is used to evaluate funding needs and, in some cases, implement new funding tools such as franchise fees. We conduct analysis on various budget scenarios to help you forecast the funding required to maintain your network of roadways. The inspection results are useful for talking with residents and City Council Members regarding necessary road improvements and are vital in justifying the funding needed to maintain city streets as part of your Capital Improvement Plans. 

A thorough pavement management plan can save you from expensive, and sometimes unnecessary, repairs. The data can help you to narrow down the areas that require preventive maintenance and rehabilitation. An effective program will emphasize maintaining streets that are in good condition to extend their service life, as preventive maintenance is less costly than rehabilitation.  

However, when streets have deteriorated and demand more extensive repair, your pavement management program allows you to plan for those projects and minimize the risks of having to make extensive changes to the project. By successfully implementing a pavement management program, you can improve the overall performance and life of your roads, saving the city and taxpayers time and money.

Sheue Torng Lee started her career at MnDOT in the MnROAD section after graduation, where she was involved in research data analysis as well as helping MnROAD in developing technical report documents. Sheue works in pavement/asset management and pavement preventative maintenance, emphasizing in pavement design and forensics.

Parking Lots Paving – Hot Mix Asphalt (HMA) Recommendations

Tom Wood, Pavement Specialist, WSB

Pavement mixes used to build streets, highways and parking lots are not the same. There are several different mix requirements that are applied to each based on the use of the surface.  Parking lots carry a low amount of daily traffic, but experience wear and tear due to static loading or from serving as a rest area.  Rest areas and truck stops have a high number of creep speed Equivalent Single Axle Loads (ESALs). ESAL is a concept developed from data collected at the American Association of State Highway Officials.  It is a road test that measures the damage relationship and the effects of axles carrying different loads.

When determining pavement mix, a parking lot’s classification must be established. Parking lots are divided into two classifications: passenger vehicle parking and commercial vehicle parking.  In some cases, parking lots serve as both passenger vehicle parking and commercial vehicle parking. These parking lots require special considerations.

The Minnesota Department of Transportation (MnDOT) has developed mix designations that are included in their Standard Specifications for Construction Book. All project documents submitted must be in accordance with the book. Mixture designations are coded and outlined for their specifications using SPWEA430C.

SP  | Design Type

Superpave, which is a gyratory compactor design used for all asphalt mixtures. This is the latest design used to replace the Marshall mix design method.

WE  | Lift course

  • WE indicates wear and shoulder wear, which is the top 4 inches of asphalt on MnDOT projects, or top 3 inches on local projects.
  • NW indicates non-wear course, which lies below the top 4 inches of asphalt on MnDOT projects or top 3 inches on local projects.

A  | Maximum Aggregate Size

2360 Gyratory Maximum Aggregate Size
A -1/2”
B -3/4”
C -1”
D -3/8”

 | Traffic Level

The traffic level is based on the ESAL or the annual average daily traffic (AADT).  Higher traffic levels require a higher-level percent of crushed aggregates.  This will reduce the effects of rutting on pavement caused by traffic loading when soft mixes are used.

Traffic Level Million ESAL AADT
2 < 1 < 2,300
3 < 3 < 6,000
4 < 10
5 > 10

30 Air Void Requirement

  • 40 for 4.0 percent air void. This is usually used on a surface with high traffic levels. The traffic helps compact the asphalt mixture.
  • 30 for 3.0 percent air void. This is usually used on surfaces or roadways with low traffic level.

C  | Performance Grade (PG) Binder Type

               2360 Designation Binder Grade
A PG 52S-34
B PG 58S-28
C PG 58H-34
E PG 58H-28
F PG 58V-34
H PG 58V-28
I PG 58E-34
L PG 64S-22
M PG 49S-34

The first numbers of the binder type are the average seven-day maximum pavement temperature (oC) and the second number is the expected minimum pavement temperature (oC). The letters dictate the traffic level. “S” grade is for standard traffic, “H” grade is for heavy traffic, “V” grade is for very heavy traffic, and “E” grade is for extremely heavy traffic.

Example – Binder Type A:

A PG 52S-34 is intended for use where the average seven-day maximum pavement temperature is 52 degrees Celsius and the expected minimum temperature is -34 degrees Celsius, under standard traffic conditions.

Parking lot mix types:

Below are some recommendations on mix types that will help enhance the overall performance of the parking lots.

Classification New Construction or Reconstruction Mill and Overlay
Passenger Vehicle Parking Only SPWEA430C SPWEA430B
Commercial Vehicle Parking SPWEA530F / SPWEA530I SPWEA530H

Aggregate Size

  • Aggregate size A is recommended due to the smaller size aggregate yielding a smooth finishing surface.

Traffic Level

  • Traffic level 4 will help limit the depression in the parking stalls for passenger vehicle parking only.
  • Traffic level 5 includes an increased percentage of crushed aggregate that helps mitigate creep speed ESAL from trucks.

Air Void Requirement

  • A 3.0 percent air void will provide a tight finishing surface and an aesthetically pleasing look.

PG Binder Type

  • The binder type used in a mill and overlay is generally lower than what is used in new construction or reconstruction. Cracks on existing underlying pavement reflect through the new overlay over time. This method is not as cost-effective as a higher binder grade. This does not mean that a higher binder grade in any mill and overlay project should not be used.  A high binder grading helps slow down thermal cracking.  It is at the discretion of the designer to decide if it is cost-effective to delay the reflective cracking.
  • On commercial vehicle parking surfaces, asphalt binder grade F is a sufficient option, but in extreme conditions a higher binder grade I (PG 58E-34) should be used to reduce rutting and shoving.
  • Surface areas where trailer landing gears are down should be designed with concrete pavement to support concentrated loads.

The recommendations above are guidelines. Additional investigation is necessary and should include coring or boring to further evaluate the subsurface conditions prior to a design work.

Forgotten cracks and sealing the joint

Tom Wood, Pavement Specialist, WSB

Sealing the joint

Over the years, both crack sealing and crack filling have proven to be very cost-effective tools in the preventive maintenance tool box. One area that has been overlooked when sealing streets and highways, however, has been the joints between two types of pavement – such as between an asphalt street and concrete curb or concrete pavement and the asphalt shoulder.

When a joint between two different pavements is left unsealed, water is unable to “jump the joint” and can end up saturating the underlying base materials and causing load-related failures. In areas where de-icing chemicals are used for snow removal operations, the flow of the residual brine can also cause the areas of infiltration to thaw earlier – increasing the likelihood of load-related damage during spring thaw.

Figure 1 – Asking Water to Jump Across a Joint

Where’s the proof that sealing these joints makes a difference in performance?

MnDOT recently did a study and published the Edge-Joint Sealing as a Preventive Maintenance Practice report, which showed that sealing the joint between concrete main line pavement and asphalt shoulders resulted in an 80% reduction in water infiltration. The assumption was that by keeping the base and sub-base drier, there would be better performance.

There are at least three methods of sealing the joints:

  1. Rout and seal if the configuration of the joint will allow a router to be centered over it.
  1. Clean and fill the joint if the concrete curbs have a pan that is too narrow to allow routing.
  1. Apply a joint adhesive to the face of the concrete and pave the hot mix asphalt against it. Joint adhesive was developed specifically for application to cold paving joints to reduce water infiltration. It has a higher viscosity than a normal hot pour sealant, which allows a thicker layer to be applied to the face of the structure.

Figure 2 – Clean and Seal Joint

A best practices guide, called Recommended Performance Guidelines for Crack Treatment, can be found on the ISSA website.

Figure 3 – Two-year-old Joint Adhesive

When sealing cracks in pavement, don’t forget about the joints along the curb line or between the shoulder and pavements.

Reference:

Minnesota Department of Transportation. Edge-Joint Sealing as a Preventive Maintenance Practice. August 2003. (MN/RC 2003-26).