Washinngton County Roads 2008 2

8/8/2019 Washinngton County Roads 2008 2

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Gravel Roads in Washington County:

“An analysis of the condition, engineering solutions, and policyoptions for sustaining the gravel road system.”

Section II: Engineering Solutions

Prepared forWashington County Board of Supervisors

Prepared byDavid Patterson, Washington County Engineer

Jake Hotchkiss, Lyle Moen, Jeremy McLaughlin

PreparedSeptember 2008



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Engineering SolutionsDuring the summer of 2008 the Secondary Roads Department performed a complete inventory of the gravel road system in the County. The inventory marked the condition, needs, and noted anyspecial circumstances of every gravel road in the county. A comprehensive review of the

available solutions was then performed to see what solution would best apply to which road.Immediate and longer term solutions were made for each road.

A variety of solutions are available for repairing gravel roads. These solutions are based onresearch done by Iowa State University and include the best practices from counties around theregion. The solutions help to restore the gravel roads to the shape and condition needed to carrynormal rural traffic. It is important to note, however, that gravel roads have a limited capacity tocarry heavy loads. Roads with high traffic volumes or large amounts of heavy loads should beevaluated for paving.

Gravel road solutions can be generally divided into four categories:

1. Adding rock surfacing2. Grading the roadway to repair deficiencies3. Upgrading a roadway for paving4. Vacating/downgrading the road classification

Some roads have an immediate need for additional rock surfacing and also have an intermediateneed for grading repair. Vacating or downgrading roadways from their Class A status is also areasonable alternative solution for some roads. Reducing the total miles of road beingmaintained would allow additional resources to be concentrated on the remaining roads.



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1. Place Gravel Surfacing

Of the 662 miles of unpaved roads in Washington County, it is estimated that 601 miles (90%)currently need gravel. Although more than 120,000 tons of gravel were hauled in 2008 alone, anestimated 316,000 tons of gravel would be needed to bring all of the roads to the standardresidents have come to expect. Figure 9 (page 16) details the various levels of rock surfacing

needs for the gravel roadways in Washington County.

Where Appropriate

• Roadway generally in good shape

• Geometry of road is acceptable

• No major drainage problems with roadway

Construction Approach

• County or contractors haul rock at specific tonnage rate

• Motor grader blades the roadway

Assumptions

• Newly rocked roads should receive 1,000 tons per mile

• Rock may be hauled at rates of 300, 400, 600, or 800 tons per mile

• 400 tons per mile is roughly equivalent to “one pass” of rock

• Recommended rates would bring gravel roads to typical condition. Continued annual rock hauling would still be required.

Photo 1: Photo of road needing gravel

Unit Cost Summary

Tonnage Rate Contract Cost (per mile) Miles Needed

300 $3,300 45

400 $4,400 213

600 $6,600 259

800 $8,800 84

TOTAL 601 miles



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Figure 9: Rock Surfacing Needs



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2. Roadway Grading

Some roadways have deteriorated geometrics that contribute to their poor condition. Gravel roaddeterioration is natural but typically occurs very slowly over time. Ditches silt in from fieldrunoff, roadway surfacing is removed during snow removal, and roadways naturally spread out

under traffic loading. However, under consistent heavy loading of large vehicles, roadwaygeometrics will deteriorate much faster. Figure 10 (page 21) shows which roads need to be re-graded for maintenance purposes. There are various levels of repair that can be done to a gravelroad ranging from minor ditch cleaning to complete reconstruction. The options are discussedbelow.

A) Clean Roadway Ditches

Where Appropriate

• Road surface generally in good shape

• Poor or blocked drainage

• Roadway remains soft because of poordrainage

• Standing water in ditches

• Location available to haul material


• Excavator is used to remove dirt out of ditches

• Material may be loaded into trucks andhauled to a nearby location

• Material may be bladed out to thebackslope or onto adjacent field

Assumptions

• Unsuitable ditch material should be hauledaway and not incorporated into theroadway.

• Excess material is spread and seeded withgrass by county crew

Photo 2: Road with full ditches and poor

drainage

Unit Cost Summary

Cost per mile: $16,400Man-hours needed: 5 man crew for 4 days per mile (160 hrs/mile)Miles of road needing solution: 39 miles



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B) Reconstruct Roadway Foreslopes

Where Appropriate

• Road is excessively wide

• Lower trafficked roads• Heavy traffic has damaged roadway causing foreslopes and traveled roadway to widen


• Project is completed in two phases

• Existing rock is stockpiled on half of roadway

• Motor graders cut foreslopes and move dirt onto roadtop narrowing and raising the road

• Stockpiled rock is moved to the half of the road that has been graded.

• Motor graders cut foreslopes on second half of the roadway

• New rock is hauled at 1,000 tons per mile

•

Roadway foreslopes are reseeded

Assumptions

• Not much rock will be salvaged during reconstruction process

• Utilizes 2 motor graders, tractor, and trucks to re-rock roadway

Photo 3: Widened road caused by heavy

trafficPhoto 4: Excessively widened road

Unit Cost SummaryCost per mile: $21,500Man-hours needed: 3 man crew for 4 days per mile (96 hrs/mile)Miles of road needing solution: 14 miles



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C) Minor Grading of Roadway

Where Appropriate

• Roadway is excessively wide

• Ditches are not draining well• Severe edge ruts have developed preventing proper roadway drainage


• Roadway is closed to traffic

• Existing rock is removed and stockpiled

• Grading crew cleans ditches and grades roadway

• Material from grading is used to raise the roadway

• Roadway is rocked at 1,000 ton/mile

• Ditches are reseeded

Assumptions

• Includes replacing cross road pipe

• Includes replacing driveway pipe

• Utilizes excavator, 6-way dozer, roller, motor grader, and 2 trucks

Photo 5: Snow traps, poor drainage, and

widened roadway.

Photo 6: Properly graded road with narrow

roadtop and no snow traps.

Unit Cost SummaryCost per mile: $50,000Man-hours needed: 5 man crew for 2 weeks (400 hrs/mile)Miles of road needing solution: 52 miles



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D) Major Grading of Roadway

Where Appropriate

• Higher traffic counts

• Snow traps are prevalent• Culverts or bridges are being reconstructed

• Poor drainage or geometry

• Entire roadway needs to be rebuilt as a result of excessive heavy loads


• Project is budgeted and planned

• Project is surveyed and designed

• Additional right-of-way is purchased

• Contract is let for construction

•

Construction completed by outside contractor including complete reconstruction of theroadway and replacement of all drainage structures

• Road is rocked at 1,000 tons per mile


Assumptions

• Cost includes $30,000 per mile for ROW acquisition costs

Photo 7: Roadway candidate for major

grading project.

Photo 8: Roadway after major grading

project.

Unit Cost Summary

Cost per mile: $205,000Man-hours needed: Contracted out onlyMiles of road needing solution: 20 miles



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Figure 10: Grading Maintenance Needs



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3. Upgrading and Paving

When traffic volumes and loads become large enough, paving a roadway may become costeffective. Even when paving is warranted, it is often not possible simply because of the cost.Although upgrading roads and paving them is not really a maintenance fix for gravel roads, some

roads have traffic volumes that exceed their capacity as a gravel road. As such, paving may bethe best long term solution for these roads. Figure 11 (page 23) depicts the gravel roads thatwarrant additional investigation in regards to paving.

Where Appropriate

• Traffic has increased above 400 vehiclesper day

• Truck traffic is too much for gravel road tosustain

• Paving road will take traffic off of adjacent

gravel roads• Road is on the farm-to-market system


• Project is budgeted and planned

• Project is surveyed and designed

• Additional right-of-way is purchased

• Contract is let for construction

• Construction completed by outsidecontractor including completereconstruction of the roadway and

replacement of all drainage structures• Road is rocked at 2,000 tons per mile


• Road paving is designed and let forconstruction

• Road is paved

Assumptions

• New road paving is completed accordingto current design guidelines

• Grading includes replacing all culvertswith reinforced concrete box culverts

Photo 9: Road graded to paving standards.

Unit Cost Summary

Cost per mile: $795,000 ($95,000 for ROW, $300,000 for grading, $400,000 for concrete)Man-hours needed: Contracted out only.Miles of road to consider for solution: 28 miles



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Figure 11: Proposed Paving Routes



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4. Vacate/Downgrade Road Classifications

Downgrading or even vacating certain roads may be a suitable solution for some gravel roads.This solution should only be considered on roads where there are ultra-low traffic volumes of traffic and no houses or businesses are present. Suitable roads would be ones that only service

the adjacent farm fields. Reducing the number of Class A (gravel) roads the County maintainswill reduce the maintenance burden on the Secondary Roads Department. Additionally,downgrading or even vacating roads would put control of certain roads in the hands of the localland owners allowing them to gate the roads to prevent unwanted or inappropriate traffic.

Where Appropriate

• Ultra low traveled roads (less than 10 vehicles per day)

• No houses or businesses present


• Notify land owners of county’s intent

• Publish notices in newspaper

• Hold public hearing

• Take official action and vacate roadway

Assumptions

• Used to reduce total miles to maintain and plow snow

• May potentially transfer ownership of roads to local residents

• Prevent houses and confinements from being built on roads that do not receive large amountsof maintenance

Photo 10: Roadway candidate for downgrade or vacation

Unit Cost Summary

Cost per mile: $0Man-hours needed: Engineering time and public hearing time only.Miles of road needing solution: 18 miles



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Figure 12: Road Candidates for Downgrade



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Cost Summary

A cost analysis of each of the proposed solutions was completed. Based on the current conditionof the gravel road system and engineering estimates of each solution, it is estimated that there is$9.8 million in needed repairs. Figure 13 summarizes these needs.

1. Place Gravel Surfacing Cost per Mile Miles Total Cost

300 Tons per mile $ 3,300 45 $ 148,500

400 Tons per mile $ 4,400 213 $ 937,200

600 Tons per mile $ 6,600 259 $ 1,709,400

800 Tons per mile $ 8,800 84 $ 739,200

Total 601 $ 3,534,300

2. Maintenance Grading Cost per Mile Miles Total Cost

Reconstruct Foreslopes $ 22,900 14 $ 320,600

Clean Ditches $ 12,000 39 $ 468,000

Minor Grading $ 52,400 52 $ 2,724,800

Major Grading $ 139,400 20 $ 2,788,000Total 125 $ 6,301,400

Figure 13: Estimated Costs of Repair Options

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Washinngton County Roads 2008 2

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