California Department of Transportation

Module 3: Visual Quality and Visual Impacts
Lesson 12: Visual Impacts

Slide 30

Module 3 Part B

Welcome back to Visual Impact Assessment Training. Part B of Module 3 of the Visual Impact Assessment training program produced by the California Department of Transportation (Caltrans) in association with the University of California at Davis (UC Davis) for the training of selected employees of Caltrans. It is now available on-line to anyone interested in how Caltrans conducts visual impact assessments.

 The presentation you are about to view is the second part of the third module. There are several modules (or, more precisely, parts of modules) which precede this presentation.  If you have advertently started with this module, you may wish to review these other presentations before beginning Part B of Module 3.

In Part A of Module 3, you learned how to define the visual quality as a product of vividness, intactness, and unity.  You also evaluated, as part of the Team Project, the existing visual quality of one of the alternatives.  In Part B, you will explore the concept of visual impacts and how to them using the FHWA VIA process. 


Slide 31

Visual Impacts

Finally!  Visual Impacts!  Let’s begin Lesson 12.


Slide 32

Visual Impacts

Let’s examine three items under this lesson—the FHWA VIA Process, especially its flow chart; the two types of assessment methods used by the FHWA; and finally how the FHWA determines visual impacts.


Slide 33

The VIA Process

Let’s review this flow diagram of the visual impact assessment process produced by the Federal Highway Administration (FHWA) as interpreted by Caltrans. 

As an analytical tool, the process is divided into two main sub-routines—one for determining changes to visual resources and the other determining viewer response to those changes.  Together, these determine the type and extent of visual impacts.  On the diagram, blue boxes record information on visual resources; yellow boxes record information about the viewer response.  Appropriately, being a combination of blue and yellow, visual impacts are recorded in a green box.

Let’s examine visual resources as defined by the blue boxes.  Recall that in Module 2 we filled in the upper left blue box—the box that states “Change to Visual Character.”   We put in a measurement of the compatibility—how compatible will the visual character of the proposed project be with the visual character of the existing scene—in that box.  (At least we did for one key view in one visual assessment unit.)

We are now about to define change to visual quality as the average of the changes the proposed project will cause to the measurement of vividness, intactness, and unity.  Later we will show how Caltrans averages the values assigned to these two boxes to get a numerical rating and descriptive narrative about the change in visual resources that the proposed project will cause to the existing scene.

The yellow boxes refer to the nature of viewers and the response they will have to changes to visual resources.  The viewer is actually a theoretical person who is a composite of all of the viewer groups who have views either from the road or to the road. 

In Module 2, we defined the exposure and sensitivity of the composite viewer.  We averaged those two measurements to get a viewer response. 

All three yellow boxes should now be filled out.  All of the blue boxes will soon be filled in.  When that is done, we will average the resource change with the viewer response to get a measurement of visual impacts.

As noted in the first module, FHWA VIA Process Concept Diagram, is available.


Slide 35

Assessment Methods

There are really two types of assessment methods that are used by the FHWA.  Both methods are useful.  Caltrans uses both, believing that they reinforce and clarify the findings.  The two types are descriptive and numerical.  

The descriptive methodology uses narrative language to describe the existing scene and the changes that will occur with the construction of the proposed project. It is used to describe visual character, visual quality, viewer exposure, and viewer sensitivity, resulting in descriptions of resource change and viewer response and concluding with a description of visual impacts.

The numerical methodology yields a set of numerical ratingsfor compatibility for the same items measured by the descriptive methodology—visual character, visual quality, viewer exposure, and viewer sensitivity—resulting  in ratings for resource change and viewer response and concluding with a numerical rating for visual impacts for each visual assessment unit.

The numerical ratings provide Caltrans with an understanding of the degree and direction of change.  The narrative descriptions provide Caltrans with an understanding of what is being changed and how it is being changed.  Both methods are equally rigorous. Both are necessary to generate appropriate mitigation measures. Together they are mutually supportive and reinforce the findings of the assessment. 


Slide 36

Numerically Rate Changes

Let’s look at one hypothetical example.  The matrix examines the numerical ratings for visual quality for Alternative Z.  Numerically, there is no change in the total visual quality rating.  However, we also know that vividness and intactness were reduced compared to the existing scene.  We also know that these reductions were offset by an improvement in unity.  Should there be mitigation?  Just going by the numbers, mitigation would not be necessary.  However, let’s see what the narrative description adds to our understanding by advancing to the next slide . . . 


Slide 37

Add Modifying Descriptors

A descriptive narrative helps us understand what the numbers mean and how to best assure that visual quality retains its existing rating or even improves.

Examine the matrix in the previous slide and compare it to the text in this slide, to answer the question, “Why are both methods of assessment—numerical ratings and narrative descriptions—necessary to get an accurate reading of visual impacts?”


Slide 38

VIA Impacts

We are now going to evaluate visual quality of three images we have previously examined for visual character compatibility.  Click on Exercise 5 - Determining Changes to Visual Quality and print this worksheet.

We will use this worksheet to record the changes to visual quality that we find while doing the exercise.  We will use both the Numerical Rating Method and the Descriptive Narrative Method.  Like the Team Project Task 5 worksheet, the numerical rating method is set up to facilitate the mathematics of the method, with the “Before” column in the middle following two “After” columns.   Notice there are two “After” columns and two “Change” Columns.  There are two columns because there are two alternatives being evaluated in comparison to the single “Before” column.

As you determine the numerical rating for each image, create an associated narrative description, noting your observations and analytical thinking in the space provided for each alternative under the Descriptive Method heading. Using your previous worksheet on visual character and what you are thinking now about visual quality, describe the changes each alternative makes to visual character and visual quality. 


Slide 39

Change in Visual Quality

These three images will be shown individually on the next three slides.  As you look at each separate image, rate the vividness, intactness, and unity of each image on a scale of 1 (low) to 7 (high).  Record your score in the appropriate box on your worksheet.


Slide 40

Change in Visual Quality

Please record your ratings for vividness, intactness, and unity of this image in the column labeled “Before.”   Refer to your notes about visual character to assist you in describing how pattern elements and pattern character generate vividness, intactness, and unity. 


Slide 41

Change in Visual Quality

Please record your ratings for vividness, intactness, and unity of this image in the column labeled “After—Alternative A.”  Again, describe the nature of the scene’s visual quality using the concepts from your earlier discussions of pattern elements and pattern character.

Be sure to be methodical about this task, you are not being asked to discuss changes to the scene, yet.  You are simply being asked to evaluate the visual quality of this proposed scene, in terms of vividness, intactness, and unity.  The discussion of changes—how the proposed scene will differ from the existing scene, will occur in the next lesson.  Right now, concentrate on the visual quality of the existing scene (the before image) and the visual quality of the proposed scenes (the after images).


Slide 42

Change in Visual Quality

Please record your ratings for vividness, intactness, and unity of this image in the column labeled “After—Alternative B.” Describe the nature of the scene’s visual quality using the concepts from your earlier discussions of pattern elements and pattern character. 

Remember to avoid any comparisons between this image and the image of the existing scene.  The comparison will come later in the next lesson on assessing visual impacts. 


Slide 43

Change in Visual Quality

Now that you have practiced conducting an analysis of existing and proposed visual quality, let’s sharpen these skills by applying them to our team project. 


Slide 44

Describing and Rating Visual Quality

Find the worksheet you previously have worked on called Team Project (Part 5) - Visual Impact Assessment Worksheet.   Remember you have already completed the “Before” column.  We now want to do the “After” column for the alternative you are evaluating at the key view in the visual assessment unit you have selected.


Slide 45

Example of a Key View

We will now determine visual quality for your alternative “after” construction at the same key view in the same visual assessment unit where you evaluated its “before” condition.

Fill in the “after” column of the worksheet one box at a time.  Determine vividness first, writing a brief descriptive narrative and then determining the numerical rating.  Follow this by filling in the boxes for intactness, then unity.

Remember that using only bullet points for the narrative is not only fine, sometimes it is preferred as a way to get to the crux of the matter and makes comparing the “Before” and “After” statements easier.


Module 3B, Lesson 13 - Assessing Visual Impacts