“If a job is worth doing,  it is worth doing right!”

Since maintenance, rehabilitation and reconstruction (MR&R) budgets are always less than the amount of money needed to upgrade every street to good condition, local agency officials must make difficult decisions as to which streets should be funded in this year’s budget.  There are two basic approaches to funding street repairs.  The most common practice is to fix the streets that are in the worst shape.  This approach is referred to as the worst-first policy.  The other approach is to keep the “good” streets in good condition.  This practice is referred to as the best-first policy.  Although Joe Q. Public will think you are crazy to spend money on streets that appear to be in good condition, the Best-First Policy really is the best policy when it comes to funding MR & R activities. The purpose of this article is to explain why the best-first policy is the best policy.

Cost of Delaying Maintenance

It is a well documented fact that the cost of repairing a pavement increases dramatically if maintenance is delayed past a certain point in the design life of the pavement.  For this discussion, the design life is defined as the total number of years a pavement is expected to last before it deteriorates to a certain level of service where reconstruction is required.  The rate of deterioration for a pavement depends on many factors such as:

• Pavement type and thickness
• Quality of initial construction
• Underlying soil type
• Traffic type and volume
• Drainage
• Type of Maintenance,if any
• Environmental factors

The deterioration curve illustrates that in the early years of a pavement’s design life, the rate of deterioration is fairly slow (assuming the pavement is properly designed and constructed). The pavement condition has gone from very good to fair.  After the pavement reaches approximately 75 % of its design life, the rate of deterioration starts to accelerate more rapidly. The pavement condition quickly drops from fair to very poor.   The pavement deteriorates another 40 % in the next 18 % of its design life.

Figure 1 also shows that for every dollar required to rehabilitate a pavement that has reached 75 percent (year 12) of its design life (this example assumes a design life of 16 years), it will take at least four to five dollars to rehabilitate a pavement if rehabilitation is delayed 3 years.  The reason for this drastic increase in rehabilitation costs can be seen by reviewing figure 2.  It shows the type of maintenance and rehabilitation techniques required to upgrade the condition of the pavement as it ages.  As the pavement ages, the type of repair necessary to properly upgrade the pavement becomes increasingly more expensive.  Figure 2 illustrates that if rehabilitation is performed at the 12-year mark, the pavement only requires preventive maintenance such as micro-surfacing or a thin overlay.  If rehabilitation is delayed until the 15-year mark, the pavement will require extensive rehabilitation or reconstruction that is much more expensive.  For example, let’s assume that if a street needed a thin overlay at year 12, the cost would be $10,000. If the overlay was delayed three years, the pavement could deteriorate to the point where reconstruction is required.  The cost to rebuild the pavement would be approximately $50,000. 
 

In the previous example, the cost of repairing the pavement went from $10,000 to $50,000 in only three years. It does not take a financial wizard to see that the worst-first approach which allows pavements to deteriorate excessively, is poor financial planning, no matter what the interest rate is.  Taxpayers are certainly not getting their money’s worth with the worst-first type of pavement maintenance program.  Therefore, it is imperative that local agencies strive to keep the “good” streets in good shape and fix the streets in poor condition when possible.

A simple cost comparison of various construction techniques shown in Table No. 1 illustrates the importance of keeping a pavement in good shape by utilizing routine and preventive maintenance measures. It is clearly shown that the “reconstruction business” is just too expensive.

Simple Philosophy

Any pavement maintenance program should be founded on the simple philosophy - keep the “good” roads in good condition, fund emergency repairs as needed, and develop a long term capital improvement fund for reconstruction of the streets in poor condition.  Since the cost of reconstructing roads is extremely costly, it is much more cost-effective to prevent the pavement from deteriorating.  The goal is to maximize the taxpayer’s investment in the infrastructure by extending its life.  This is accomplished with the following tasks:

 1.  Seal Cracks -  crack sealing prevents water from infiltrating into the subgrade, thereby 
                               maintaining the ability of the soil to adequately support the pavement.

2.  Fix Potholes -  this will prevent them from becoming larger and will stop water from 
                              entering the subgrade.

4. Overlays -  should be used to prevent rapid deterioration of aging pavement.  In addition 
                        to sealing the surface, an overlay will add some additional strength.  Although 
                        overlays are necessary, it is more cost effective to prevent the pavements 
                        from deteriorating to this point for as long as possible by utilizing crack 
                        sealing, patching and surface treatments.

The following simple example shows how preventive maintenance extends pavement life, thereby, stretching the limited maintenance budget as far as possible.  For this example, it will be assumed that the road is one mile long and twenty feet wide, and the repair costs from Table 1 will be used. Assumptions are a twenty-year design life (before reconstruction), good original construction, and neglect the time value of money and intermittent repairs.  Although the last two assumptions were neglected for the sake of a simple comparison, the outcome would not change drastically if they were included (in normal situations).

In the situation below, the pavement is allowed to deteriorate for 15 years at which time a $60,000 overlay is required.  In situation b, the pavement receives micro-surfacing (preventive maintenance) while the pavement is still in good shape at year 10.  A second application is applied at year 20.  Although situation b receives two treatments as opposed to one for situation a, it was still a lot cheaper.  The simple morale of the story is preventive maintenance pays !
 

Is “Best-First” Possible?

A common question asked is, "How do we implement a preventive maintenance program when we don’t have enough money to fix the streets that really need to be fixed now?”   The correct answer is to let the pavements in poor condition go and spend the money on preventive maintenance.  Some local spots that are safety hazards such as car-eating potholes must be fixed.  A separate capital improvement budget should be developed for reconstruction projects.  Although this is the correct answer, it is not practical in the real world.  Most town councils would tar and feather anyone who would suggest such a crazy plan.  However, not attempting to change from the worst-first policy is cheating the public.  Therefore, a compromise is necessary.

The realistic compromise is to allocate a small portion of the budget to preventive maintenance.  Fifty to seventy five percent of the budget spent on preventive maintenance would be great, but ten percent is better than nothing.  And every year after the first, try to increase the portion of the budget which goes toward preventive maintenance.  At the same time, try to develop a capital improvement budget for reconstruction projects.  The quicker the preventive maintenance budget grows, the quicker a municipality will be able to get a handle on this seemingly out-of-control MR&R budget.  If done properly, at some point in time, the overall MR&R budget will actually decrease.  What a novel thought!  Believe it or not, this is possible to achieve if the agency officials are willing to make some tough decisions!

As for determining what MR&R technique should be used when, that is the easy part.  A good pavement management system will be able to handle that part.  The hard part will be for the municipality to determine how much money it is willing to put towards preserving the existing roadway system.  Remember, in the long run, it is much cheaper to keep good streets in good shape.