5/17/11

Land Use Academy 1

Map Reading 101: Using and Reading Maps and Plans

A Key Skill for Land Use

Commissioners

Paula Stahl, LLA, ASLA, AICP

Land Use Educator

Green Valley Institute

5/17/11

Land Use Academy 2

How most of us react to

maps and reports...

As the map is

rolled out at

the P&Z

meeting...

Wonder what

those lines

mean?

Where is

this ?

I m

hungry.

Oh, geeze I ll

never get

home in time

for the game

Goals of this Workshop

the sources of maps and plans

how maps and plans are used

fundamental elements of maps and plans

how to evaluate maps and plans

To Understand:

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Land Use Academy 3

Maps, Plans...What s the Difference?

Maps show physical features of the

natural or built environment at

established scale and orientation.

Plans are engineered drawings made

to scale showing existing physical

features of a site and proposed

changes to accommodate

development.

What is the purpose of this Map or Plan?

Town Planning

Regulatory

Wetland Impacts (IWW)

Subdivision (Planning)

Site Plan (Zoning)

Maps, Plans...What s the Difference?

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Land Use Academy 4

Go from the general to the specific

Maps, Plans...ways they are used

Maps are 2-dimensional representations of

complex landscapes

A Map is not the Territory -Alford Korzybski

at one point in time!

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Land Use Academy 5

Key Elements of Maps

Identifiers

Legends

Scale

North Arrow For orientation purposes

Key Elements of Maps

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Land Use Academy 6

Title

Creation & Revision

Dates

Source

Cartography Road Mapville, CT

XYZ GROUP/

ABC ASSOCIATES

500 Longitude Boulevard Mapville, Connecticut 06001

860-555-5555

Title Block Information on who/what/when etc

Key Elements of Maps

Legends Provide a guide to the symbols used

Key Elements of Maps

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Land Use Academy 7

Scale Shows relative size of objects

Key Elements of Maps

35 20 !

Scale Shows relative size of objects

Graphical Scale Written Scale

1:12,000 (ratio)

1 = 1,000 (equivalent)

Graphic scales are the most reliable!

Beware of Xerox Distortion

Key Elements of Maps

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Land Use Academy 8

Measuring Distances

Rulers and Scales

Engineering Scale

1 = 10

1 = 20

1 = 30

1 = 40

1 = 50

1 = 60

1/8 = 1

1/4 = 1

1/2 = 1

3/4 = 1

1 = 1

Architects Scale

Map Scale Meaning

10 1 inch = 10 ft

20 1 inch = 20 ft

30 1 inch = 30 ft

40 1 inch = 40 ft

50 1 inch = 50 ft

60 1 inch = 60 ft

Measuring Distances

Engineering Scales 40 ft

240 ft 400 ft

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Land Use Academy 9

But, can be

used at other scales

Scale Meaning Adjustment

80 1 = 80 ft Use 40 scale and

multiply by 2

100 1 = 100 ft Use 10 scale and

add a zero

200 1 = 200 ft Use 20 scale and

add a zero

2000 1 = 2000 ft Use 20 scale and

add 2 zeros

Measuring Distances

Engineering Scales 400 X 2 = 800 ft

X 2

Plan Scale Meaning

10 1 inch = 10 ft

20 1 inch = 20 ft

30 1 inch = 30 ft

40 1 inch = 40 ft

50 1 inch = 50 ft

60 1 inch = 60 ft

PLAN SCALE = 40

1 =40

Measuring Distances

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Land Use Academy 10

1 =40

Measuring Distances

Distance ?

55

Factoid: What is an acre?

200

200

True acre 9% larger = 43,560 sq. ft. (R-1)

Builder s acre = 40,000 sq. ft (R-40)

5/17/11

Land Use Academy 11

Wonder what

those lines

mean?

Map Reading Skills

Maps

Many maps are in the

form of topographical

maps aka topo

Interpreting a 3D

world in 2D

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Land Use Academy 12

Topography

Contour Interval is the difference between lines,

USGS topo has 10 ft contours and site plans 2 ft contours

Index Contours are the lines labeled with an elevation

Contours: an imaginary line that connects points of equal elevation

Contours always connect,

but not always within the map boundaries...

Topography

This could be the edge of a

presented map

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Land Use Academy 13

Cross-sections are sometimes used to represent 3-D objects in 2 dimensions.

Topography

Cross-sections are sometimes used to represent 3-D objects in 2 dimensions.

Topography

Vertical scale sometimes

exaggerated to better show change

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Land Use Academy 14

every 5th contour is an index contour shown in bold

contours far apart show a gentle slope

contours close together show a steep slope

a series of concentric contours ending in a small closed circle

or oval shows a local hilltop

contours at a stream form a V that always points uphill

contours very close together show a cliff

a spot elevation is a point of known elevation used as

a pt of reference for surveys.

a benchmark (BM): point of known position & elevation

used as a pt of reference for surveys.

green areas show forest cover; white areas denote fields

a contour interval is the vertical distance b/w contours. 10 on

topos; 2-5 on site plans

contour lines of a ridge are in a U that always points downhill

Plan Reading - Tips

Water flows

downhill...

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Land Use Academy 15

Slope direction is calculated perpendicular to

the contour lines.

Because

it is the steepest

slope.

Topography

Water flows

downhill...

Slope

Change of elevation between two

points, over a given distance

Slope

Distance

Ele

vati

on

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Land Use Academy 16

Slope

Percent Slope =

10 ft

20 ft

Change in Elevation

Distance X 100

(10 / 20 ) X 100

= 50% slope

Why is Slope Important?

If too Steep:

- potential erosion

- soil stability

- safety

10 ft

20 ft

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Land Use Academy 17

Why is Slope Important?

If too flat:

- storm water may not drain

- may flood

0 ft

20 ft

Your turn!

Find or calculate the following:

- What s missing?

- Highest elevation

- Elevation of Pt. A

- The distance between Pts A & B

- The change in elevation between A & B

- The percent slope between A & B

- Which is higher C or D?

- Which direction would water flow from C? D?

- Where would that water leave the map edge?

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Land Use Academy 18

Answers

1.-What s missing?

North Arrow, Legend, Source

2.-highest elevation

582 ft

3.-elevation of Pt. A

570 ft

4.-the distance between Pts A & B

1,000 ft

5.-the change in elevation between A & B

100 ft [B is 470]

6.- the percent slope between A & B

10% 100/1000 = .1

7.Which is higher C or D?

C [C is 510]

8.Which direction would water flow from C? D?

9.Where would that water leave the map edge?

As the map is rolled out at the P&Z meeting ...

Hmm. What are

they doing?

5/17/11

Land Use Academy 19

Evaluating the Project

Site Development

• Land Clearing

• Grading

• Roads

• Structures

Management Plans

• Erosion & Sedimentation

• Stormwater

Land Clearing

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Land Use Academy 20

Land Clearing

Limit of Construction Activity

Grading

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Land Use Academy 21

Grading

Grading

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Land Use Academy 22

Grading

Existing Contour Lines

More level when contours are farther apart

Grading

Existing Contour Lines

Proposed Contours

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Land Use Academy 23

• Type

• Size

• Location

Structures

• Septic Systems

• Wells

• Roof leaders

• Footing drains

Other Structures

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Land Use Academy 24

Other Structures

Maps, Plans What s the Difference?

Maps show physical features of the natural or built environment at established scale and orientation

Plans are engineered drawings, made to scale, showing existing physical features of a site and proposed changes to accommodate development.

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Land Use Academy 25

Types of Plans

Survey – the site before proposed intervention

Layout – the proposed locations of added features

Grading & Drainage – changes to topography

Utilities – location/connection to systems

Demolition Plan – what s being torn down

Planting Plan – what plants where

Details – drawings of specific features at a large scale

Erosion and Sediment Control Plan – protection of the site and any wetlands during construction

TAKE IT APART &

START ASKING

QUESTIONS

03/12/05

Plan Reading who? what? where? when?

Are they qualified?

What s the project

name?

Where is it?

Where s

north?

What s the scale?

Type of Map?

Who made the map? What s it all Mean?

When drawn?

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Land Use Academy 26

Find the roads

Plan Reading – take it apart

and the sidewalks and centerline of road right-of-way

03/12/05

Plan Reading – take it apart

Property Line Stream

03/12/05

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Land Use Academy 27

Plan Reading – take it apart

03/12/05

Plan Reading – take it apart

Topography

602+2

03/12/05

5/17/11

Land Use Academy 28

Plan Reading – take it apart

Topography

03/12/05

Plan Reading – take it apart

100-Yr Flood

03/12/05

5/17/11

Land Use Academy 29

Plan Reading – take it apart

Vegetation & Stonewalls

03/12/05

Plan Reading – take it apart

Utilities

03/12/05

5/17/11

Land Use Academy 30

03/12/05

Plan Reading

HP LP

– put it back together

Plan Reading – Who & Why

Zoning Commission: • Establish zoning regulations • Review site plans for adherence

Planning Commission: • Plan of Conservation & Development • Establish Subdivision regulations

• Review plans for subdivisions

Inland/Wetland Commission: • Review site plans and subdivisions to determine

impact to wetlands

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Land Use Academy 31

Plan Reading –

Why are you looking at these plans?

There is a proposal to change this site

What s your role as a commissioner? To make sure this proposal meets the requirements

set out by your commission's regulations

What s your goal?

To ask as many questions as it takes

03/12/05

03/12/05

Plan Reading – Proposal

Is this a copy?

Is that really the scale?

5/17/11

Land Use Academy 32

03/12/0

5

take it apart Plan Reading

03/12/05

take it apart Plan Reading

5/17/11

Land Use Academy 33

Plan Reading focus in

Plan Reading

What s the lot size? Regulations: 1 ac.

Lot is 1.34 ac.

ask questions

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Land Use Academy 34

Is that enough frontage? Regulations: 100 min.

122

40

Double Frontage

Plan Reading

Is the building within setbacks? Regulations: 40 front 10 side

27

46

131

Plan Reading

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Land Use Academy 35

How many parking spaces?

9

4 5

8 8

2

Regulations: 41 + 2

34 + 2

Plan Reading

Where s the limit of wetland review?

Did Inland / Wetland Commission approve?

Plan Reading

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Land Use Academy 36

What s the distance from the intersection? Regulations: 75

62

108

Plan Reading

Where s the dumpster?

Is it screened? Can it be accessed easily?

Plan Reading

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Land Use Academy 37

Is that a drive-up?

Does drive-up queue conflict with parking?

Are drive-ups permitted here?

Plan Reading

Other questions?

Plan Reading

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Land Use Academy 38

Plan Reading – Another Proposal

Subdivision The division of a tract or parcel of land into three or more parts or lots for the purpose, whether

immediate or future, of sale or building development expressly excluding development for municipal,

conservation or agricultural purposes

Plan Reading – Another Proposal

It s Your Turn Again !

5/17/11

Land Use Academy 39

Answers for Exercise 2

LP

HP

1. Is anything missing from the Layout Plan? Professional Seal & Signature 2. What s the scale of the Layout Plan? 100 scale 3. Where are the steeper slopes? the flattest

area? 4. Locate the High and Low Points HP LP

How does water flow from the HP to the LP?

5. Would Inland/Wetlands need to approve? Yes Outline the upland regulated area. 6. What type of subdivision is this? R-1/2 Open Space 7. If an Open Space subdivision, is there

sufficient open space set aside? Yes 8.18 ac. out of 15.65 ac. 8. Do all proposed lots meet the minimum lot

size? Yes 9. Do all the proposed lots meet the minimum

frontage required? Yes, the narrowest is 78 10. Does the length of this new cul-de-sac road

meet regulations? Yes, it s 920 in length 11. What other questions do you have?

Questions??

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Land Use Academy 40

Key Concepts:

Know the purpose of your map or plan

Remember: The map is not the territory. Verify with field walks, if necessary.

Always look for the significant map elements: north arrow, title blocks, legends, etc.

Always ask: what is the scale of this map? Is it appropriate for the purpose?

Try to visualize topography use tricks when necessary.

The maps and plans are YOURS! Draw on them, make notes, anything that will help you formulate questions and understand the proposal.

If in doubt, ASK! If still in doubt, ask again!

The next time the map is rolled out at the P&Z

meeting...

What s the

frontage?

Is that

enough for

a sight line?

I think they re

actually

reading my

maps!

How steep

is that

slope ?