Components of a plan set

Engineers are a valuable resource for the ADOT Blog. We quote them, film them and use their knowledge so we can better explain to you many of our more complex transportation topics.

Without the expertise of ADOT’s engineers, this blog just wouldn’t be the resource that it has become over the past three years. We definitely appreciate our engineers, which is why we’re so glad to share today’s guest blog post with you.

It comes from one of ADOT’s Engineers in Training. We blogged about this innovative program back in 2012, but basically EITs follow a structured program working in varied sections within ADOT. Their time is divided into training blocks that last two and four months. A few of the blocks are mandatory and others are selected by the EIT.

Our guest blogger Elizabeth Weil made the choice to rotate through ADOT’s communications division for one of her blocks! Her time here has included learning about the many ways ADOT communicates with the public. Today, she writes about construction plans and explains some of their different components…

By Elizabeth Weil

Transportation Engineering Associate

We draw them, we review them, and we use them during construction, because they tell us what to do. Roadway plans are common around ADOT amongst designers and construction personnel, but you’ve probably never seen them for yourself. Here are just a few things that we include in plan sets.

Pavement structural sections (above) describe the layers of a roadway. In this example, above the subgrade (the ground below the roadway material) goes 5 inches of AB (aggregate base, a specific size of rock), then a layer of AC (asphalt, or “asphaltic concrete”), a tack coat (an adhesive oil used to make layers of asphalt stick to each other), and another layer of AC on top.

A typical section shows (above) which structural sections are used in specific areas. They’re accompanied by station limits (in this case 1086+00.00 to 1089+02.07). Those numbers refer to a specific location in the same way a milepost would. This typical section also gives a distance from the right-of-way line to the centerline of the road, the slope of the roadway, and widths of the lanes and shoulders. This way, we know exactly where the roadway will go and how big it will be. Think of the typical section as a cross-section of the roadway; if you were driving, you’d be moving into or out of the page.

Typical Section

This is just part of a sheet showing the plan view of the roadway (a bird’s-eye view). There is a lot of information on each of these sheets- this section of roadway has a taper (where the width of the roadway changes), guardrail (the numbers in diamonds are pointing at it), and right of way (the dashed lines near the outside). Numbers in the shapes are referring to a summary sheet which I haven’t included in this post, but each summary gives much more information (such as guardrail lengths).

Lastly, if you were wondering, we don’t usually have numbers in red; these screenshots were taken from our drafting guidelines which exist so we can make our plans as consistent as possible to avoid confusion.