6A-9: Edge Profiles

Table of Contents

The vertical profile of an edge return should be flat enough to provided a comfortable transition between the cross slopes of two roadways, and yet not so flat to cause a drainage problem. This section provides guidance on how to develop an edge profile which is smooth, constructible, and prevents drainage problems. Examples are provided detailing the steps involved in developing an edge profile.

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Guidance for Intersections without Curb Ramps

An edge profile for an intersection without curb ramps should incorporate the following guidance: 

  1. Minimum cross slope of 0.5%. 
  2. Maximum cross slope of 6.0%. 
  3. Cross over crown breaks should be less than 5% and with preferred values less than 4%. 
  4. Desirable change in cross slope is 1% in 12.5’.
  5. The algebraic difference in grade lines along the edge profile at the control points should not exceed 1.5%. Grade differentials greater than 1.5% are difficult for contractors when forming an intersection return.
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Guidance for Intersections with Curb Ramps

Guidance for an edge profile with curb ramps will be issued later. 

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Steps to Develop an Edge Profile

  1. Place longitudinal jointing lines
  2. Determine tie-in elevations
  3. Locate control points
  4. Determine elevation of control points
  5. Develop edge profile and adjust elevations to limit algebraic difference in grades
  6. Check cross slope
  7. Check change in cross slope 
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Example 1-Typical Rural Ramp Intersection

The first example is an intersection of a ramp and a side road.

Step1: Place longitudinal jointing lines

Locate longitudinal jointing lines. The joint line is used as the staking line. It should be concentric to the edge of the return and offset 10’ – 16’.

Roadway diagram showing a merge area with a highlighted longitudinal joint line and a close‑up detail indicating a minimum 2‑foot offset.

Figure 1

 

Step 2: Determine tie-in elevations

Calculate the edge of the pavement elevations at the tie-in points at each end of the return. These elevations are of the beginning and ending points of the edge profile.

Diagram showing a main line and a diagonal branch with two marked tie‑in points where the routes connect.

Figure 2

Step 3: Locate control points

Diagram showing a main line with a diagonal branch and two labeled tie‑in points marking where the connections occur.

Figure 3

 

Step 4: Determine elevation of control points

Use the NC% of the side road and the CS% of the ramp to determine the elevations at each end of the staking line.

Use a transverse cross slope of 3% on the return to determine the initial elevations of the control points. 

Ramp tie‑in diagram showing pavement cross‑slope transitioning from crown to ramp cross‑slope, with a callout of the grade‑line relationship.

Figure 4

Step 5: Develop edge profile

Use the elevations at the tie-in and control points to develop adjacent initial grade lines. Then adjust the elevations until the algebraic difference between adjacent grade lines is 1.5% or less. 

Grade‑profile diagram showing slope changes between elevation nodes, showing how different slope combinations affect alignment continuity.

Figure 5

Grade‑profile diagram showing slope changes between elevation nodes, showing how different slope combinations affect alignment continuity.

Figure 6

Intermediate VPI points are sometimes needed to establish an edge profile with grades lines with algebraic difference of 1.5% or less. 

The additional VPI points should be added at even 10’ increments along the edge return, since forms are normally 10’ long.

Step 6: Check cross slope

After adjusting the elevations of the control points, calculate the resulting transverse cross slope on the return. The resulting cross slopes should preferably be in the 2%-4% range, with 0.5% and 6.0% being the minimum and maximum cross slopes.

If a cross slope is greater than 6.0% or less than 0.5%; adjust the elevation of the control point and revise the edge profile.

The resulting cross slopes should not create a cross over crown break of 5% and preferably less than 4%. Inverted crown breaks should be avoided.

Several iterations of adjusting the control point elevations may be necessary to optimize the edge profile, transverse cross slopes, rate of change and cross over crown break. 

Cross slopes should create smooth transitions, but should not fluctuate back and forth. In other words, cross slopes should gradually increase and/or decrease, but should not alternate at successive control points. 

Ramp‑to‑roadway diagram showing a curved profile grade line with marked slope segments of 5.40% and 3.00%.

Figure 7

Step 7: Check change in cross slope

The change in cross slope between transverse staking lines should be less than 1% in 12.5 feet (or 0.8% in 10’). 

If the change in cross slope is greater than 1% in 12.5 feet; adjust the elevation of a control point, revise the edge profile, and calculate the resulting cross slope.

Ramp‑connection diagram showing a curved profile grade line with a marked arc length between two slope segments labeled 5.00% and 3.00%.

Figure 8

 

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Example 2-Intersection of a major and minor roadway

Step1: Place longitudinal jointing lines

The second example is of an intersection of a major and minor roadway. The intersection of the two roadways occurs within a horizontal curve of the major roadway and the minor roadway has a stop sign island.

Roadway‑intersection diagram with a highlighted circular callout showing a longitudinal joint line and a detail view noting a minimum 2‑foot offset.

Figure 9

Step2 : Determine tie-in elevations

Roadway‑merge diagram marking two tie‑in points where a new ramp section connects to the existing road.

Figure 10

Step3 : Locate control points

Roadway‑interchange diagram showing two curved lanes meeting, with several red control‑point markers outlining the geometry of the merge curve.

Figure 11

Step 4 : Determine elevation of control points

Intersection diagram showing a minor road joining a curved major road, with callouts of cross‑slope transition from crown to superelevation.

Figure 12

 

Step 5 : Develop edge profile

Line‑profile diagram comparing elevation nodes and grade changes to show how different adjustments alter the slope between start and end.

Figure 13

Line‑profile diagram comparing elevation nodes and grade changes to show how different adjustments alter the slope between start and end.

Figure 14

 

Step 6 : Check cross slope

Roadway‑design diagram showing a curved merge area with red‑labeled slope values marking grade changes along the connection.

Figure 15

Roadway‑design diagram with a curved red arc marking a transition curve between two road segments, annotated with slope percentages and arc‑length labels.

Figure 16

 

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Chronology of Changes

Chronology of Changes
DateRevision Description
  
  
7/21/2026New 2026 Update
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