PROCEEDINGS of the Twentieth Paving and Transportation Conference

Sponsored by:

Department of Civil Engineering
The University of New Mexico
Albuquerque, New Mexico

By Dennis Polhill
President
Pavement Management Systems, Inc.
Lakewood, Colorado

Pavement Management is the process of making decisions about pavements. It is a daily activity of agencies responsible for pavements. In the context in which “pavement management” is used today, it infers utilizing more information in order to make those decisions better.

In pavement management, decisions are considered to be made at two levels: the project level and the network level. A total pavement management system includes both project level analysis, network level analysis and an information exchange back and forth between the two levels.

PROJECT LEVEL

Project level analysis is the process of looking intensely at a particular pavement for the purpose of optimizing the rehabilitation strategy being considered for that pavement. Project level analysis is considered

an engineering application of pavement management information.

Project level analysis may include consideration of several pavement parameters such as ride quality, skid resistance, rutting, structural capacity. The single parameter considered most is structural capacity. The best way to clarify the definition of project level analysis is through example applications.

PROJECT LEVEL ANALYSIS APPLICATIONS

Overlay Design

To make the best overlay decision, questions of thickness, type, timing and alternates must be considered. A “too-thin” overlay will result in premature failure and loss of some of the benefit (extension of serviceability) of the overlay. A “too-thick” overlay results in the expenditure of too much money now and in the loss of the option to put those dollars into another needy project. In Denver, a quarter of an inch of A. C. overlay equates to about $8,000 per mile. In Edgewater, Colorado, this type of analysis saved an overlay project $19,500.

Reconstruction Design

If grades are to remain the same during a reconstruction project, considerations similar to an overlay design are in order. “Can the existing structure contribute to or be used in the new structure?” In Frostburg, Maryland, this question was raised. By acquiring proper information the design engineer was able to determine which sections required rebuild and which sections could be rehabilitated. The estimated savings to the project was over $200,000.

Street Widening

If grades are to remain the same during a widening project, considerations similar to the reconstruction design are in order. “Can the existing structure contribute to or be used in the new structure?” or “What

needs to be done to the existing pavement to make it serviceable as the center two lanes of the project?” This question was raised during a project in Aurora, Colorado. In the final analysis, it was determined that the existing 2-lane roadway would be structurally sufficient with a minor overlay and isolated locations of additional structural padding or patching. The theoretical savings on this project was over $400,000.

Street Acceptance

The same type of analysis can be done on a new street. The obvious application is for acceptance of streets built by developers. Everyone has seen or heard of cases where as soon as a street is accepted by the municipality, it fails. The process merely requires that the street must demonstrate its ability to perform for a period of time as specified by the municipality. Some method of nondestructive testing and professional engineering analysis must be used. This approach will give cities the assurance they need that the facilities they accept will perform.

Assessment of Impacts

Assessment of impacts includes a variety of possible applications of project level pavement management information.. How do you determine the amount of permit fees to be charged for an overweight load moving through your jurisdiction? How does the change of a bus route effect a particular street? How do you determine what the load limits should be on your roads? What is the consequence of a major change in traffic volume or traffic con-figuration? A new development goes in that results in an increase in traffic loading both during and after construction. How much rehabilitation should reasonably be charged to the development and when should the work be scheduled? Timely rehabilitation resulting from assessment of conditions such as these can protect against premature failure of.pavement facilities. Project level analysis gives the capability of addressing these issues.

NETWORK LEVEL

Network level analysis is the process of looking at an entire system . (or network) of pavements. This is done to answer network-wide questions, such as which projects should be considered for rehabilitation. Network level analysis is considered a management application .of pavement management information. Some network level questions are:

  • What is the current level of service?
  • What will happen to the level of service over the next few years if the budget is set at “$????”?
  • What streets should receive priority consideration for maintenance of rehabilitation?
  • What would be the impact of a change in traffic characteristics?
  • What maintenance activity is required to get maximum benefit out of monies expended?

Rehabilitation Costs

By referring to Figure 1, it can be seen that rehabilitation costs increase by over 4 to 5 times if rehabilitation is deferred only 12% of a pavement’s design life. For typical pavements, 12% amounts to about 2 years. In view of this fact, deferred rehabilitation is very expensive. Good management dictates that rehabilitation occur at a time so as to derive the greatest benefit (or extension of serviceability) possible. The problem becomes very complex since each different pavement structure has a different point in their service lives.

Figure 1

An important point can be concluded here. Unless a jurisdiction has all the money it needs for rehabilitation, it is almost certainly a mis-take to program rehabilitation on a “worse-first” basis. Maximum benefit cannot be derived from the limited public funds available if an agency binds itself to a “worst-first” programming philosophy.

Maintenance Costs and Serviceability

Maintenance costs increase as serviceability declines. The increasing commitment to maintenance tends to extend serviceability but at a higher cost and lower service level than if rehabilitation was performed. This fact has been verified by several studies. The most widely known is research done by the Utah Department of Transportation, which was referenced in NCHRP Report #58 (see Figures 2 and 3). For all categories of roadway the least cost strategy was “A”, where the highest service level was sustained. The highest cost was strategy “D”. at which rehabilitation was deferred until such point that substantial increases in maintenance activity was required in response to public pressure to sustain service-ability-at a minimum acceptable level. Strategy “D” was UDOT’s current mode of operation.

Figure 2:

Figure 3

 

Figure 3:

Figure 6

Network Example

The best documented case of the successful implementation of a network level pavement management system is the Regional Municipality of Ottawa-Carleton, Canada, whose Transportation Director-is Michael J. E. Sheflin,

P. E. In 1980, Ottawa-Carleton’s road budget was 14% less in actual dollars and 43% less in inflated dollars than it was in 1977. At the same time average service level was improved. Shefiin gives credit for this accomplishment to the progressiveness of his council.

REFERENCES

1) Haas, R.C.G., and Hudson, W.R., “Pavement Management Systems”, McGraw-Hill, 1978.

2) Tessier, G.R., and Haas, R.C.G., “Pavement Management Guide”, Road and Transportation Association of Canada, 1977.

3) Chong, G.J., “Pavement Maintenance Guidelines”, Ontario Ministry of Transportation and Communications, 1980.

4) Chong, G.J., Phang, W.A., and Wrong, G.A., “Manual for Condition Rating of Rigid Pavements”, Ontario Ministry of Transportation and Communications, 1975.

5) Chong, G.J., Phang, W.A., and Wrong, G.A., “Manual for Condition Rating of Flexible Pavements”, Ontario Ministry of Transportation and Communications, 1975.

6) Eaton, R.A., and Joubert, R.H., “Pothole .Primer”, Special Report 81-21, U.S. Army Corps of Engineers, 1981.

7) Kobi, D., “ARAN, An Integrated and Automated Road Inventory Tool”, American Public Works Association, 1981.

8) Karan, M:A., “Municipal Pavement Management System”, University of Waterloo, 1977.

9) Sheflin, M.J.E., “Your Choice: Bad Roads At High Cost Or Good Roads At Low Cost”, Oklahoma State University, 1980.

10) Haas, R.C.G.,. “Combining the Priority Programing of Pavement Maintenance and Rehabilitation”, Transportation Research Board, 1982.

11) Yoder, E.J., and Witczak, M.W., “Principles of Pavement Design”, John Wiley and Sons, Inc., 1975.

12) AASHO, “AASHO Interim Guide for Design of ,Pavement Structures – 1972″.

13) Sheflin, M.J.E., “Good’ Roads _DO Cost Less”, Rural and Urban Roads, October, 1980.

14) NCHRP #5.8, “Consequences of Deferred Maintenance”, Transportation Research Board, 1979.

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