Cornell Local Roads Program

Save Money by Spending More

With budgets stretched as tight as they are nowadays, we are all looking for ways to save money and use our limited dollars wisely. What do you think the reaction of the board would be if you asked for twenty-five percent more money per ton for cold patch? Will they happy? They should be! By spending a little more for cold patch, and using the ‘Throw and Roll’ method, you will actually save money in the long run.

Between now and next spring you will probably have to send out a crew to patch a few potholes. Hopefully you have an aggressive pavement management plan and have addressed as many drainage problems as you can. Even so, we will all see a few potholes this winter and next spring.

Potholes form when excess water is present under a pavement, especially pavements carrying heavy traffic. Excess water compromises the integrity and strength of the supporting layers and allows the pavement to weaken and break down prematurely. If the pavement is not thick enough, or the loads are too heavy, potholes will form. To fix the potholes and bad spots, ideally you would box out the bad material, take care of any drainage problems, add enough new material to handle the expected traffic, and place it in good weather.

However, in the winter and early spring it is difficult to properly patch potholes. In addition to the excess water, and the instability brought about by freezing and thawing, the weather is typically lousy. Nonetheless, you need to quickly place material into a severe pothole in order to improve safety, at least temporarily. If done correctly, a short-term patch should survive until a long-term repair can be made.

Some highway departments own or rent spraypatch trucks to fill in the potholes. These work by forcing a pressurized mixture of hot asphalt emulsion and stone into the pothole. The resulting mixture is already compacted as it is placed and will survive for quite a while.

However, this is not an option that many departments have available. Most of us use “Old Reliable,” a truck filled with cold patch that a crew simply throws into the holes. The biggest problem with this method is exactly that, the method.

Simply throwing the cold patch into the hole and expecting traffic to finish compaction is unrealistic, and bound to fail. What will happen instead is that the traffic is going to scatter the cold patch, and you will have to go back and fill the pothole again... and again... and again. Typical one month survival rates for such Throw and Go patches are less than ten percent!

Simply rolling over the patch with the truck tires (Throw and Roll), improves the survival rate to twenty five percent or more! This is mainly due to the high pressure tires and weight of the truck slowly pressing the patch material into the hole. While it takes a bit longer and costs a bit more in labor and equipment costs, compacting the patch with the truck stabilizes the material and keeps traffic from knocking it out of the hole.

The other problem is the patch material we are usually using. While cold patch is relatively inexpensive on the first run, it does not last as long as it could, and is especially prone to failure when the pothole is filled with water or snow. When are we most likely to be doing an emergency patch? In the middle of poor weather with the pothole filled with water or snow!

Proprietary materials with polymers included as part of the mix are designed to work in these conditions. They are not as prone to stripping and shoving as standard cold mixes. Survival rates with proper Throw and Roll methods and proprietary cold patch can be over eighty percent!

The NYS Office of General Services (NYSOGS) has statewide bids for all kinds of highway and non-highway related materials. The OGS website address is provided below. To find cold patch, go to the Commodity Contracts page and select the Group-Award number (315) for Highway Bituminous Materials. The direct webpage address is given below. The proprietary mixes are listed as Plant Mixed Modified or Cold Mixed Modified. Last December a ton of standard cold patch would cost from just under $40 to a bit more than $55 if you picked it up at the plant (FOB). The proprietary patch was $72-80 per ton, almost twice as much in some places!

In the last nine months, the cost for cold patch has gone up by over $28 per ton! For a plant near Ithaca that means the prices today are $81 per ton for standard mix and $101 for the proprietary mix. Ouch! Nonetheless, the more expensive material still COSTS LESS in the long run, when applied properly, using Throw and Roll.

The table below shows the typical cost to patch about 100 medium sized potholes, which would require about 20 tons of fill material. The INITIAL COSTS of using the Throw and Go method with standard cold patch are definitely lower than using Throw and Roll with proprietary material. However, after two weeks the crew has to go back and refill the first patches that failed. Then two weeks later a THIRD trip fills any reopened or newly failed potholes. If more patches survive, each subsequent trip will be less expensive.

The survival rate in the table below is the number of patches that usually survive for two weeks. The table also shows the typical number of potholes that have to be re-filled on the second and third trips. The total shows the costs after three trips.

Typical Costs of Repairing 100 Potholes Using Different Methods and Materials
Patching Method and Material Throw & Go (Standard Patch) Throw & Roll (Standard Patch) Throw & Roll (Proprietary Patch)
Material price per ton $81 $81 $101 $101
Material cost (20 tons) $1,624 $1,624 $2,023 $2,023
Labor $845 $1,126 $1,126 $1,126
Equipment $250 $334 $334 $334
Initial cost - 1st trip $2,719 $3,084 $3,483 $3,483
Survival rate 10% 25% 50% 80%
# of potholes to re-fill 90 75 50 20
Cost of 2nd trip $2,447 $2,313 $1,742 $697
# of potholes to re-fill 81 56 25 4
Cost of 3rd trip $2,202 $1,735 $871 $139
Potholes remaining 73 42 13 1
Total Cost $7,368 $7,131 $6,095 $4,319

After THREE trips, a lot of the patches filled using the Throw and Go method have failed again and the potholes are still present! With a fifty percent (or higher) survival rate, the patches using proprietary mixes with Throw and Roll are less expensive in the end and most of the potholes stay filled.

The proprietary cold patch mix you should use is the one that works for you. Some mixes are harder to spread and some hold up slightly better in different weather and traffic conditions. Try a truckload of the modified material and compare the results to your current patch survival rate. Choose the material that is the least expensive with the best result.

It is better to get the right material and use the right technique. It will save money and improve safety for the traveling public.

See? You CAN make the board (and the citizens) happy, by spending MORE per ton!

Summer 2008

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This work by the Cornell Local Roads Program (CLRP) is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.