County engineer devises a new strategy for gravel roads

·7 min read

Sep. 3—The engineer's office has been gathering data for the past six months in order to develop a new strategy for maintenance and assessments of gravel roads.

Jasper County Engineer Michael Frietsch introduced supervisors to his Granular Road Assessment & Maintenance Strategy (GRAMS) on Aug. 16, but it will take more meetings and work sessions to arrange the finer details. In preparation for those future meetings, Frietsch gave the supervisors a bit of homework to do.

"Here's your homework for the week," Frietsch said while passing out documents. "What you got there before you basically is the stabilization program, the reclamation program, the resurfacing program and the spot rock programs and then the blade map. Everything is all basically hooked to the blade territories."

The GRAMS details Frietsch's new approach to gravel or granular roads. It specifically addresses the amount of rock used for each service, the cycles in which the county would apply to its schedules and the data used to determine which roads are the best candidates.

Similar to the county's comprehensive plan, Frietsch said the GRAMS will be a living document that would need to be revisited every few years and adjusted. However, the supervisors still have to hash out the details through work sessions. Frietsch is also taking supervisors' comments into consideration.

"This is going to take a while," Frietsch said. "This is a primer."

Currently, granular road maintenance is spread out of over 10 blade territories. Each territory is comprised of about 90 miles of roads, not counting the Level B roads (dirt roads with little maintenance). Frietsch said there are about 917 miles of Level A roads (standard gravel roads) in Jasper County.

Territories are assigned a dedicated motor grader and operator; the engineer's office has four motor grader sheds — in Reasnor, Colfax, Baxter and Kellogg — that they all operate out of. The primary objective of those blade operators and motor graders is to maintain the cross slopes to ensure drainage.

Other objectives include eliminating wash boarding, preserving road stone, cleaning ditches and shaping of the roads.

In addition to the ongoing maintenance of the blade operators and territories, Jasper County has an annual contract rock program where staff place 150 tons of road stone per mile on gravel roads. Frietsch said his office typically divides the contract rock between the north and south halves of the county each year.

"We did the north half this year. Theoretically, we would switch over to the south half next year unless we decide to switch it up with this new strategy," he said.

The secondary roads department also runs regrade program on an annual basis. Usually crews regrade 20 to 30 miles of roads per year. Frietsch said the work involves pulling in the ditches and shoulders, getting the road back to a correct width and shape. About 600 tons of road stone is used per mile on regrades.

"Some of the issues we've had with regrades — and I think it's going to be resolved a little bit with the aggregate spreader we've purchased now — is we have a lot of variability in the depth that we end up applying it when you tailgate it on there," Frietsch said. "The other reality is: 600 tons per mile is nothing."

Frietsch ultimately wants to increase the amount of road stone use on regrades. Other work using the granular budget consists of mainly "spot rock" repairs. From what Frietsch can tell, the county may be taking money from other areas in order to "keep feeding that animal." It is a continuous demand.


To determine priority roads, the county looks at assessment data. Gravel roads are assessed based upon annual average daily traffic (AADT) and also the percentage of truck use, which is established using traffic counters. The AADT data comes from the Iowa County Engineers Association Service Bureau.

Using that data, the engineer's office can then determine which roads or candidates would be best suited for maintenance. Frietsch divided road segments into four types of maintenance groups: stabilization, reclamation (formerly regrades), resurfacing and minimal maintenance.

Frietsch explained requirements needed for each category:

—Stabilization candidates require an AADT greater than or equal to 100 or a traffic count between 50 and 100 and greater than 10 percent truck use.

—Reclamation candidates would have traffic counts between 50 and 100 and less than 10 percent of truck use.

—Resurfacing candidates need an AADT between 30 and 50.

—Minimal maintenance candidates need a traffic count of less than 30.

Frietsch's approach to stabilization involves cleaning and reshaping ditches and pulling shoulders as needed, reshaping roads as needed and getting road widths correct. At this point, the engineer's office is looking at using a 50-50 mixture of recycled asphalt pavement and road stone at a rate of 3,000 tons per mile.

This should give roads an extra four to five inches of thickness, Frietsch said. With the new aggregate spreader, the county engineer said it will allow crews to get the mixture to the thickness it needs to be and keep it uniform. Chemical treatment products will then be applied to the roads.

Two miles of roads have already received this treatment and staff are frequently inspecting the segments to see how they will hold up. Stabilization also fits into a five-year cycle, Frietsch said. The initial goal would be to conduct 10 miles of stabilization per year.

Reclamation is similar to the county's regrade process, but Frietsch changed the name to better reflect the duty. Crews are still cleaning and reshaping the ditches with the motor graders and pulling in the shoulders. But instead of putting down 600 tons of rock per mile, the county would put down 1,200 tons per mile.

"We're probably going to use the 'dirty rock' because I want to get those fines to have the chemical reaction with the soil, the lime — like lime stabilization," he said. "And we're going to put it right down the center of the road with the aggregate spreader so we can put down a good thickness."

Frietsch said the problem with the current regrade process is the amount of rock used per mile and the inconsistency in thickness across that mile of rock.

Right now, the county engineer is envisioning an eighty-year cycle on regrades, which gives the county an average of 36 miles of candidates each year. Frietsch said his initial goal is to do about 20 miles annually. The county will evaluate the candidates to determine which projects should be a priority.

Resurfacing would involve cleaning out ditches as needed. But Frietsch wants to shift the process to placing 450 tons of road stone per mile, per quadrant. Which means resurfacing will be conducted in four-year cycles. Right now the county is using 150 tons per mile every other year; about 300 tons over four years.

Jasper County could utilize contract rock hauling and not only include the resurfacing candidates but also the previous year's reclaimed roads. Frietsch said the reclaimed roads will have 1,200 tons per mile the first year. The next year he envisions another 450 tons per mile.

Spot rock will be used on minimal maintenance roads, the roads with less than 30 cars traveling per day. The amount of spot rock — 50 tons per mile, per year — will be allocated annually for each blade territory. Frietsch said he is going to try to secure stockpile locations in each territory or in strategic locations.

With this plan, Frietsch hopes it gives the county flexibility to address the critical roads needs while also tending to on-the-spot maintenance.

Jasper County Supervisor Brandon Talsma requested supervisors review the information over next few weeks before revisiting the GRAMS at a future open meeting. Talsma requested a board work session to take place at the end of the Sept. 6 meeting.

"This is something that I think is going to take several months probably to digest, talk about funding options and everything else," Talsma said. "It's not something that we're just going to get done in two weeks."

Contact Christopher Braunschweig at 641-792-3121 ext. 560 or