# <Horizontal Alignment> Signs and Plaques

#### belongedto

##### Senior Member
Source: U.S. Department of Transportation-Federal Highway Administration-Manual on Uniform Traffic Control Devices-2009 Edition Part 2 Figure 2C-1
-Horizontal Alignment Signs and Plaques
I understand the meaning of these signs, but I don't understand the use of "horizontal" and "alignment".

• #### Chez

##### Senior Member
I would say that it means that these arrows represent movement on a horizontal plane e.g. The first one means walk ahead and then turn left.

#### kentix

##### Senior Member
These are road signs, so the first one means you are approaching a 90° curve to the left.

I have never heard that use of horizontal alignment but apparently, as Chez says, it represents signs describing changes in direction to the left or right.

The numbers are speed limits in miles per hour that are suggested for going aground those curves.

#### Chez

##### Senior Member
That's not quite all I meant. How would a 2-dimensional sign indicate 'go upstairs and turn right'? You might think the first sign could mean that as the line of the arrow moves 'up' towards the top of the sign. You'd probably have to look up Vertical Alignment signs and Plaques (or similar) to find the answer to that, but the title of THESE plaques shows that they indicate moving along the horizontal plane that you are already on before making the turns shown on the signs.

#### RM1(SS)

##### Senior Member
The guy who came up with "horizontal alignment" must have been paid by the letter. I would call them "turn signs".

#### kentix

##### Senior Member
These are road signs, Chez. There is no going upstairs in a car. You follow the road. If it goes up, you go up. But these signs are warning you about upcoming turns that you should be ready for, especially the ones using the speed limits. The upward direction on the sign simply indicates forward motion on the road.

I agree with RM1 that whoever came up with the description of the category did a very poor job of using an intuitive label.

#### Chasint

##### Senior Member
What we need for context is to know what other types of Signs and Plaques there are.

belongedto - do you have a link to the text? If not, can you give us some of the other headings and diagrams?

#### kentix

##### Senior Member
Here is use in context:

Here's an article about road design. It uses the term horizontal alignment, apparently it's a standard term in the road designing business, but not vertical alignment, from what I can see.

Geometric design of roads - Wikipedia

Horizontal alignment in road design consists of straight sections of road, known as tangents, connected by circular horizontal curves.[2] Circular curves are defined by radius (tightness) and deflection angle (extent).

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#### jwood

##### Member
The MUTCD is a technical document with an intended audience of highway (road) engineers. An average person would not use this wording.

As others have stated, horizontal alignment is a more technical way of saying "these signs warn of turns or curves in the road," i.e., that the alignment of the roadway turns horizontally to the left or right. Signs that warn of changes in vertical alignment would warn of things like steep downhill grades (especially important for large trucks.)