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Asset Management | Bridge Technology | Operations | Pavement

A Quick Check of Your Highway Network Health

Quick Check Presentation

By
Larry Galehouse, Director
National Center for Pavement Preservation

And
Jim Sorenson, Team Leader
FHWA Office of Asset Management

Notes: Today, highway agency managers and administrators face the daunting assignment of allocating resources to address the needs of their highway network. This "Quick Check" will determine the adequacy of their resource allocation effort with minimal calculations. All that is required is the following information:

  1. The total number of "lane-miles" in the agency's network,
  2. The present or planned program actions within a given year. Program actions include reconstruction, rehabilitation and various pavement preservation (e.g., resurfacing, crack sealing, chip seals, etc.).

Example:

Agency Highway Network

Network Size = 4,356 lane miles

Notes: Let's assume we have a highway network of 4,356 lane-miles. This network could be representative of a county, city, or a state DOT district, region or division. However, the "Quick Check" always works regardless of the network size.


Notes: Assume we could plot the condition of every pavement segment in the highway network. The plot might appear as shown in this graph.

The horizontal-axis represents years of Remaining Service Life (RSL) and the vertical-axis depicts the percentage roads in the network that have that RSL. For example, in above chart pavement segments having an RSL=5 comprise nearly 2% of the entire pavement network.

So what is Remaining Service Life? It represents how many years of life a pavement has until it will reach zero life, or RSL=0.

So what is Zero Life (RSL=0)? If the agency has established zero (RSL=0) correctly it represents two things.

First, the public is not satisfied with the condition of the road. Telephones begin to ring and the agency is forced into a reactive mode to maintain the pavement serviceability.

Second, and more importantly the only financially feasible option the agency has, is to reconstruct or rehab the road. Maintenance forces can generally patch and fill potholes, but the expenditure is not gaining pavement life. Preservation is no longer an option. Reactive actions only maintain a limited degree of serviceability.

Let's assume a worst-case scenario – no funds will be available for highway work (of any kind) next year.

What will happen to the network and this graph? Every pavement segment will lose (on average) one year of life. The graph columns will move one year to the left. So pavement segments with an RSL=9 will now have an RSL=8, an RSL=5 will now have an RSL=4, and so on.

Think about it this way! Mother Nature and traffic continually deteriorate our pavements through environmental extremes and the mechanical actions of tire wear. Each cause of deterioration is making a withdrawal of life from the highway network.


Notes: Pavements with an RSL=1 now have an RSL=0. Note that these pavements coming from RSL=1, are added to the pavements already in the RSL=0 category. This group represents "dead" pavements that can't be revived without reconstruction or major rehabilitation.

Background Information

Most highway agencies have a limited budget and can only address a small percentage of their highway network through reconstruction or rehabilitation projects. For example, if their entire annual budget were used to reconstruct or rehabilitate the worst pavements, it would amount to somewhere between 2% and 4% of the network.

One year later, another stack of projects fall into the "dead" pavement column, or RSL=0. These columns are similar to ocean waves hitting the beach. Each year another group of pavements move into the RSL=0 column.

This graph illustrates a much larger issue, which is, working only on the network's worst roads is a losing proposition and a bad strategy. Few agencies can ever receive enough funding to stay ahead of the backlog of poor pavements, by only reconstruction and rehabilitation efforts. Pavement preservation is also necessary, by adding life to roads in good condition and moving them to the right by increments of 2 to 10 years, depending on the treatment used.

The goal of pavement preservation is to manage the network by extending pavement life and reducing the backlog of roads in poor condition. This will permit agencies and the contracting industry to accurately predict future resource needs.


Agency Highway Network = 4,356 lane miles

Each year the network will lose

4,356 lane mile years

Notes: Let's assume we have a highway network of 4,356 lane-miles. This network could be representative of a county, city, or a state DOT district, region or division. However, the "Quick Check" always works regardless of the network size.


Reconstruction Evaluation
ProjectLane MilesDesign LifeLane Mile YearsLane Mile CostsTotal Cost
#12225 yrs550$463,425$10,195,350
#21830 yrs540$556,110$10,009,980
Total = 1,090$20,205,330

Notes: Continuing our bank account analogy, deposits must be made to maintain financial solvency. The reconstruction, rehabilitation, and pavement preservation projects initiated during one year represent deposits to the network, offsetting the losses of lane-mile-years.

In the example, the highway agency plans two reconstruction projects for next year. Project #1 will involve 22 lane-miles of pavement using a 25 year design life. When the 22 lane-miles are multiplied by a design life of 25 years, the result is 550 lane-mile years. The same calculation is performed on Project #2. The sum of the reconstruction efforts represents 1,090 lane-mile years, synonymous with a network deposit for reconstruction.


Rehabilitation Evaluation
ProjectLane MilesDesign LifeLane Mile YearsLane Mile CostsTotal Cost
#32218 yrs396$263,268$5,791,896
#42815 yrs420$219,390$6,142,920
#53212 yrs384$115,848$3,707,136
Total = 1,200$15,641,952

Notes: The same calculations are performed for the rehabilitation program planned for next year. The example has three projects. Multiply the lane-miles of each project by the design life and the result is lane-mile years.

The sum of the rehabilitation efforts represents 1,200 lane-mile years, synonymous with another network deposit.


Pavement Preservation Evaluation
ProjectLane MilesLife Ext.Lane Mile YearsLane Mile CostsTotal Cost
#101122 yrs24$2,562$30,744
#102223 yrs66$7,743$170,346
#103265 yrs130$13,980$363,480
#104167 yrs112$29,750$476,000
#105810 yrs80$54,410$435,280
Total = 412$1,475,850

Notes: The final calculations are performed for the pavement preservation program planned for next year. The same calculation method is used as in the previous examples for reconstruction and rehabilitation, with one notable exception. When evaluating pavement preservation treatments, it is appropriate to think in terms of "extended life" rather than design life. The term design life, as used in the reconstruction and rehabilitation examples, relates to a new pavement's structural adequacy. The goal of pavement preservation is not to improve the structural adequacy of the pavement, but rather stop or slow various distresses caused by traffic volume, environment, and so forth.

Since pavement preservation treatments are applied to pavements that are in good structural condition, there is some degree of Remaining Service Life (RSL). Pavement preservation treatments must not be applied to projects that have an RSL=0.

In the example, the agency plans five pavement preservation projects for a total of 412 lane-mile years.


Network Trend
Required: 4,356 lane mile years
Programmed ActivityLane Mile YearsTotal Cost
Reconstruction (40 lane miles) $$$$1,090$20,205,330
Rehabilitation (82 lane miles) $$$1,200$15,641,952
Pavement Preservation (84 lane miles) $$412$1,475,850
Total = 2,702$37,323,132

Notes: The proposed programmed activity is summarized by the highway agency. The totals are as follows: 40 lane miles for reconstruction, 82 lane miles for rehabilitation, and 84 lane miles of pavement preservation. This amount of work restores 2,702 lane-mile years to the network at a total cost of $37,323,132.

The automation depicts dollar symbols ($). The dollar symbols represent comparative costs of the action (similar to a "AAA" or "Diners Club" cost rating). Substantial funds are necessary for reconstruction and rehabilitation projects, while pavement preservation projects use significantly smaller funding amounts.


Network Needs Summary
Network Size (needs)4,356 (lane mile years)
Programmed Activity2,702 (lane mile years)
Deficit = 1,654 (lane mile years)

Notes: The most important consideration is how the proposed program addresses the system's overall need – in other words, how much are you putting back into the road compared to how much it is losing?

This network loses 4,356 lane-mile years and the proposed program adds 2,702 lane-mile years. As a result the network needs exceed the program size by 1,654 lane-mile years.

Any programmed activity less than the network needs is running a deficit and worsening over time.

A program that meets the network need is maintaining the status quo. The network is not getting better, but not getting worse.

A program that exceeds the network needs is improving the pavement condition.

Too often highway agencies accept the results without adjusting the programmed activity.


Notes: This slide contains various animations.

If the system's needs are not being met by a proposed program, we should adjust the program activities to see if the needs can be met within the given budget. When a highway agency readjusts the program activity, tough choices must be made. In this example, the reconstruction program was slightly downsized from 40 lane miles to 31 lane miles (deferring the other 9 lane miles will be deferred until the following year), and the rehabilitation program was also downsized from 82 lane miles to 77 lane miles (deferring the other 5 lane miles until the following year).

This portion of the program costs were reduced by $6.1 million, but note that as the programs were downsized, so was the total of lane-mile years. Next, we will see how that money could be applied elsewhere in the program to restore more lane-mile-years.

Background – reconstruction can be deferred – a year's delay will not significantly affect the scope of a reconstruction project.


Program Modification
Savings = $6,101,940 Needs = 1,999 LMY
Preservation TreatmentLife ExtLane MilesLane Mile YearsTotal Cost
Concrete Reseal4 yrs31124$979,600
Thin HMA Overlay10 yrs16160$870,560
Micro-surfacing7 yrs44308$1,309,000
Chip Seal5 yrs79395$1,104,420
Crack Seal2 yrs5061,012$1,296,372
 1,999$5,559,952

Notes: The system still needs 1999 of LMY in order to meet the annual deterioration. The $6.1 million redirected from the reconstruction program could be applied to a variety of less expensive pavement preservation projects in such a way that the 1999 LMY can be met.

Note – this presumes that there are suitable candidate roads (still in good condition) for the preservation actions.


Revised Network Strategy
Required: 4,356 lane mile years
Programmed ActivityLane Mile Years
Reconstruction
( 31 lane miles )
820
Rehabilitation
( 77 lane miles )
1,125
Pavement Preservation
( 2,083 lane miles )
2,411
Total =4,356

Notes: When the highway agency readjusted the program activity, the network need was achieved. In fact, because the $6.1 million was not exhausted, a net savings of $541,988 can be used to perform additional work.

Through careful network analysis there is a potential to actually improve the pavement network condition.


Quick Assessment Method

  • Establishes Network Need
  • Evaluates
    • Reconstruction
    • Rehabilitation
    • Preventive Maintenance
  • Incorporates
    • Design Life
    • Life Extensions

Notes: Funds allocated for reconstruction and rehabilitation projects must be viewed as investments in the infrastructure. Conversely, funds directed for preservation projects must be regarded as protecting and preserving past infrastructure investments.

The Quick Assessment Method can be used on any size network with accuracy. It establishes network need, evaluates programmed activity, and incorporates design life and preservation life extensions.


Network Needs Worksheet
Required: _______ lane-mile years
Programmed ActivityLane-Mile Years
Reconstruction
( ____ lane-mile X ___ yrs )
_______
Rehabilitation
( ____ lane-mile X ___ yrs )
_______
Pavement Preservation
( ____ lane-mile X ___ yrs )
_______
Total = _______

Note: This slide can be used to insert your own data to determine if you are putting as much back into your system as the system is losing.

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Updated: 11/01/2012