Design of roads

[nagatalluri]

Guys:

Is there any specification for subgrade thickness selection based on soil type. I am looking for roads in a wind farm. The roads will be used only during the construction for the turbine delivery and construction activities. Later they are used rarely.

We are looking for something like a county roads.

Please suggest any specifications

Thanks
N Talluri

 

[Ron]

Thickness design of pavements is based on repetitive use. If the use is expected to be light, then you look at minimum design thicknesses and constructability. For example, you would not want to use less than 6" of graded aggregate base material, since the aggregate size can be up to about 3" and you would not want punching shear problems with the aggregate. Second, for constructability purposes, you will need at least 1-1/2" of asphalt. As a third consideration, the subgrade must be stable enough to get compaction in the base material. For loose sands, this will require stabilization of the subgrade material so that compaction in the base can be achieved.

 

[racookpe1978]

Windfarms require routine maintenance visits and frequent access and regular maintenance requiring both high density 18 wheeler trucks and mobile cranes, and very, very frequent ow density (regular pickup trucks and small panel trucks).

Typical though of the windfarm planning though: Build as if no repairs and access will be required. The same roads used for maintenance are used for construction, and those loads will destroy cheap roadbeds. If not right on dry rock and firm sand, the construction roads you propose will tear up rapidly, erode out, and be useless.

 

[nagatalluri]

Guys:

Thanks for the inputs. I am wondering if there is any specification (AASHTO or US DOT) specifications for temporary or access roads construction?

Please let me know
NT

 

[oldestguy]

This subject probably should be called low volume roads, not temporary. If you make them suitable for the construction equipment at the beginning, they likely will do fine for long term. My suggestion is that you contact the county highway department in that area for their recommendation also either with or without a surfacing of asphaltic concrete. Most of the county highway departments I have been in touch with have long term experience as to what works and what does not. They probably do not use any particular design guide. Another source would be a state university ag-engineering department which advises farmers on various aspects of their farms. That department likely can give some good leads. Finally, don't pass up local paving contractors. Many times they have to provide access to jobs and need to build a road for their heavy vehicles and know hoe well various "treatments' do the job. In my experience, I find those that build things usually are very generous in their time to discuss these types of things. They can also give info on local sources of aggregate, etc. Dosing this, you likely will get the best bids for the work, since you will write the specs to fit local conditions.

 

[Ron]

OG is correct...if they can handle the initial construction traffic, then they are likely good for the long term. AASHTO has a guide for design of low volume pavement structures, also.