Companion Guide to Video January 2019

www.fhwa.dot.gov/federal-aidessentials

Today, most agencies recognize the role 

of preventive maintenance treatments in 

slowing deterioration, extending the life of 

pavement, and reducing the need for costly 

repairs.

Historically, agencies react to poor conditions 

by either patching potholes or removing or 

replacing the top layers of asphalt to restore 

the pavement surface. A reactionary approach 

often results in conditions fluctuating from 

good to poor over time and is less cost 

effective. However, much like doing regular oil 

and air filter changes for your car, pavement 

preservation treatments— such as crack sealing 

and slurry seals—work well when done in a 

timely manner before the structure is damaged. 

Agencies expect their asphalt pavements to last 

at least 20 years. To maintain that lifespan, 

what is the most cost-effective preventive 

maintenance treatment? 

That depends largely on the condition of the 

pavement and local conditions, such as traffic 

and weather patterns, pavement materials, and 

community expectations of a smooth ride. For 

example, is the pavement condition:

• Excellent, or very smooth

• Good, mostly smooth with minor cracking;

• Fair with wheel path cracking; or

• Poor or very poor with frequent alligator 

cracking, rutting, and potholes?

Let’s review commonly used pavement 

preservation treatments and see how one local 

agency re-evaluated its preventive 

maintenance regime to lower pavement lifecycle costs. 

Federal-aid Program Overview

Asphalt Pavement Preservation

Preservation techniques to extend asphalt pavement life.
Federal-aid Essentials for Local Public Agencies

Crack and fog seals are most appropriate for 

pavements in excellent to good condition and 

can extend the life of pavement by 1 to 4 years.

Routine infiltration of water and debris 

deteriorates pavement and weakens its 

foundation. Fog Seals — an application of a 

specially formulated asphalt emulsion — seals 

narrow cracks, restores lost flexibility to the 

pavement surface due to asphalt oxidation, and 

protects pavement structure. 

In addition to cracks being vulnerable to water 

intrusion, pavement can develop minor rutting 

and other defects that create poor surface 

friction characteristics. 

When existing pavements develop these 

conditions but are still in good condition, some 

agencies are able to extend the useful life of 

pavements by 3 to 7 years by sealing the 

surface with a more robust combination of 

asphalt and aggregate. 

Chip seals consist of an application of an asphalt 

emulsion covered immediately with crushed 

rock which combine to form a single layer, 

whereas, slurry seals include a single layer of a 

paving mixture composed of asphalt emulsion, 

aggregate - or very small crushed rocks- and 

water. 

If the pavement is still in good condition but 

shows minor signs of rutting in addition to 

water intrusion and surface defects, micro 

surfacing can be a good option. 

When applying micro surfacing to the surface of 

asphalt, crews use a paving mixture composed 

of asphalt emulsion, aggregate, water, and 

chemical additives. Micro surfacing mixtures are 

durable and cure quickly, a priority when quick 

traffic return is important. 

Once pavement conditions become fair or poor, 

thin and ultrathin overlays can extend their 

useful life by 5 to 12 years. 

Thin overlay materials consist of a dense-graded 

mix of asphalt and aggregate prepared in a 

plant. Following cold milling to remove surface 
Federal-aid Essentials for Local Public Agencies

defects, crews apply a less than 2-inch layer of 

materials.

Ultrathin overlay materials consist of a designed 

asphalt and small stone mixture that is 

prepared in a plant and hauled to the site. 

Following the application of a thick layer of 

liquid asphalt tack coat, crews apply less than 1 

inch of the ultrathin material mixture. 

Now let’s see how one municipality reassessed 

its pavement preventive maintenance 

guidelines in an effort to extend pavement life.

For residential streets designed to last 25 years

or more, the municipality has followed these 

guidelines since the late 1990’s:

• Year 2: Seal cracks.

• Years 5, 12, and 18: Apply a slurry seal.

• Year 25: Mill and replace the surface.

The city engineer reviewed the data in the 

pavement management information system 

focusing on the reported pavement condition 

and observed distresses. The municipality’s 

emphasis on elapsed time between treatments 

has produced large fluctuations in the annual 

street maintenance budgets due to major 

repairs being needed outside of the cycle; this, 

in turn has caused the delay of preventive 

maintenance activities which is leading to more 

streets in poor condition.

Based on the available annual budget, he 

concluded that the city’s overall pavement 

condition could remain stable, and the overall 

life of the pavement network could be 

extended several years without substantial 

rehabilitation if the city:

• Prioritize maintenance based on pavement 

condition rather than elapsed time between 

treatments; 

• Crack fill and seal pavements that are in 

good condition;

• Fog seal roadways to prevent loss of 

aggregate when raveling appears; and

• Micro Surface roads when they show signs 

of minor rutting. 

As the example illustrates, agencies make 

better use of available funds when they analyze 

pavement life-cycle costs and re-evaluate their 

preventive maintenance guidelines. 

Preventive maintenance can:

• As with your car, extend the useful life of 

the pavement, 

• Make effective use of available funding, and 

• Reduce the frequency of costly and 

disruptive rehabilitation and reconstruction 

projects. 
Federal-aid Essentials for Local Public Agencies

If some of the techniques highlighted here are 

not in your agency’s tool box, contact your local 

FHWA Division office or State DOT or ask other 

agencies how they have effectively used these 

treatments to manage their pavement network 

and incorporated these activities into Federalaid projects. 
Federal-aid Essentials for Local Public Agencies

The content of this 

document is not a 

substitute for 

information obtained 

from State departments 

of transportation, 

appropriate FHWA 

Division Offices, and 

applicable laws. 

Scenarios have been 

simplified for emphasis 

and do not necessarily 

reflect the actual range 

of requirements 

applicable to the 

scenario or this topic. 

This document was 

created under contract 

number DTFH61-13-A00001 by the Federal 

Highway Administration, 

U.S. Department of 

Transportation, and is 

offered to the public to 

heighten and focus 

awareness of Federal-aid 

requirements within the 

local public agencies 

community and 

reinforces the 

importance of these 

necessary policies, 

procedures, and 

practices.

This Companion 

Resource is the script 

content for the video 

production of the same 

name. 

Additional Resources

The FHWA Policy Guidance Center page has technical information and guidance 

materials for Pavement Preservation.

https://www.fhwa.dot.gov/pgc/index.cfm?ddisc=52&dsub=1014

See this FHWA Center for Accelerating Innovation (CAI) webpage for details of 

preservation techniques.

https://www.fhwa.dot.gov/innovation/everydaycounts/edc_4/pavement.cfm

This website of the Foundation for Pavement Preservation provides a toolbox with 

links to research reports and details for the wide variety of preservation techniques. 

http://fp2.org/preservation-toolbox/

This pavement management guidance document provides the necessary tools, 

procedures and practices for network-level pavement condition data collection. 

https://www.fhwa.dot.gov/pavement/management/qm/data_qm_guide.pdf

Promotional brochure from FHWA effort to clarify when, where, and how of 

pavement preservation that can be distributed to stakeholders and management. 

https://www.fhwa.dot.gov/innovation/everydaycounts/edc_4/factsheet/pavement_

preservation.pdf