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## Section 5: Spiral Curve Data

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### Spiral Curve Defined

Spiral Curve documents the location and all the elements necessary to define a route segment that curves at both a varying rate and a constant rate. Curved segments have a varying rate curve at one or both ends, used as a transition from the straight segment that precedes or follows the curve and the constant rate curve segment, or normal curve, in the center. The Spiral Curve requires either three or four location points to document:

• A four-point spiral curve consists of a normal curve with two varying rate segments at each end, the second being a normal curve. All four curve points must completely document a four-point spiral curve: TS SC CS ST
• A three-point spiral curve consists of a normal curve with only one varying rate segment at either end (see Figure 13‑2 below):
Anchor: #i1008911Points of a Spiral Curve

Point

Description

Point 1

The Tangent to Spiral point, i.e., the TS point, the beginning of the first varying rate segment

Point 2

The Spiral to Curve point, i.e., the SC point, the ending of the first varying rate segment and beginning of the normal curve segment

Point 3

The Curve to spiral point, i.e., the CS point, the beginning of the second varying rate segment and ending of the normal curve

Point 4

The Spiral to Tangent point, i.e., the ST point, the ending of the second varying rate segment

• Figure 13-2. Route curves at a varying rate between TS and SC, at a constant rate between SC and CS, then at a varying rate between CS and ST.

Curve Id—Unique seven-digit identification number the system assigns to each Spiral curve. The system stores the number on the record containing the SC point of a spiral curve.

Note:

• Do not add a spiral curve within the limits of another curve
• Do not change the location of a curve to fall within the points of another curve
• Update either the location points of the spiral curve or the data attributes associated with the spiral curve. If updating both, input two separate transactions
• Do not update if the Signed Highway is incorrect; delete and re-enter the curve record
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### Input—Spiral Curves

Follow these input instructions to add spiral curve. Input each of the spiral curve points in sequential reference marker order, i.e., the TS point must precede the SC point, which must precede the CS point, which must precede the ST point:

Step

Action

Input

1

(For instructions to log onto the system, click this link)

From the TPP Database Maintenance Menu, select Update-Code 12H and press <E>; the TPP Database Maintenance Submenu appears

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2

Input X next to Spiral Curve and press <E>; the Spiral Curve submenu appears

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3

Input Location Key fields

4

Input Supplemental Location Key fields

• CS Curve Point Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement
• ST Curve Point (if applicable) Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement

5

Input Spiral Curve fields and press <F2>; the system updates TRM with the new information and displays the message “Transaction completed successfully”

• Curve Type S
• Delta Angle measurements:
• Degrees, whole degree values 000 to 179
• Minutes, whole minute values 00 to 59
• Seconds, seconds to one decimal, values 00.0 to 59.9
• Left/Right, direction (L or R)
• Tangent Length 1, in miles to three decimals, values 00.000 to 99.999
• Tangent Length 2, in miles to three decimals, values 00.000 to 99.999
• Curve Degree Angle measurements:
• Degrees, whole degree values 00 to 89
• Minutes, whole minute values 00 to 59
• Seconds, seconds to one decimal values 00.0 to 59.9

6

• To select Baseline Bearing, PI Curve, or Normal Curve additions, data, press <F3> to exit back to the TPP Maintenance Submenu
• To input another Update-Code, press <F3> twice to exit back to the TPP Database Maintenance Menu
• To exit back to the TRM Main Menu, press <F10>

(For instructions to log off the system, click this link)

-

Follow these input instructions to delete spiral curve:

Anchor: #LMHENJNHDelete Spiral Curve

Step

Action

Input

1

(For instructions to log onto the system, click this link)

From the TPP Database Maintenance Menu, select Update-Code 11H and press <E>; the TPP Database Maintenance Submenu appears

-

2

Input an X by Spiral Curve and press <E>; the Spiral Curve submenu appears

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3

Input Location Key fields

• Signed Highway System, Number, and Suffix
• From Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement
• OR
• To Reference Marker Number (PT, SC) and Suffix (closest to SC point)
• (+) or (–) To Reference Marker (PT, SC) Sign
• To Reference Marker (PT, SC) Displacement (as the distance from the Marker to the SC point)

4

Input Supplemental Location Key fields

• OR
• Reference Marker Number and Suffix (closest to the CS Curve point)
• (+) or (–) Reference Marker Sign (positive if the direction to the CS Curve point is past the Marker, or as negative if the direction to the CS Curve point is prior to the Marker)
• Reference Marker Displacement (as the distance from the Marker to the CS Curve point)
• OR
• Reference Marker Number and Suffix (closest to ST Curve point)
• (+) or (–) Reference Marker Sign
• Reference Marker Displacement (as the distance from the Marker to the ST Curve point)

5

Input remaining fields and press <F2>; the system retrieves record data from TRM. A prompting message “Press PF2 to confirm or PF 11 to cancel” appears

Curve Type S

6

Repress <F2> to confirm deletion; the system displays the verification message “Transaction completed successfully” and deletes all data records associated with the deleted spiral curve attributes

OR Press <F11> to cancel deletion; the system takes no action

7

• To select Baseline Bearing, PI Curve, or Normal Curve deletions, press <F3> to exit back to the TPP Maintenance Submenu
• To input another Update-Code, press <F3> twice to exit back to the TPP Database Maintenance Menu
• To exit back to the TRM Main Menu, press <F10>

(For instructions to log off the system, click this link)

-

Follow these input instructions to update spiral curve location:

Anchor: #i1008998Update Spiral Curve Location

Step

Action

Input

1

(For instructions to log onto the system, click this link)

From the TPP Database Maintenance Menu, select Update-Code 13H and press <E>; the TPP Database Maintenance Submenu appears

-

2

Input an X by Spiral Curve and press <E>; the Spiral Curve Data screen appears

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3

Input Location Key fields

NOTE: Input only the PC or PT point for curve updates

• Signed Highway System, Number, and Suffix
• From Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement
• OR To Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement

4

Input the Supplemental Location Key fields and press <E>; the system retrieves record data from TRM. A prompting message “Enter new Reference-Marker location” appears

• CS Curve Point Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement
• ST Curve Point (if applicable) Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement

5

Input the update location fields and press <F2>; the system updates the location and the verification message “Transaction completed successfully” appears. The original request for the current location to update displays for another update transaction

• Update the PC point, any ‘From’ Reference Marker fields
• Update the CS point any ‘From’ Reference Marker fields and/or
• Update the ST point, any ‘From’ Reference Marker fields
• Update the PT point, any ‘To’ Reference Marker fields

6

• To select Baseline Bearing, PI Curve, or Normal Curve, press <F3> to exit back to the TPP Maintenance Submenu
• To input another Update-Code, press <F3> twice times to exit back to the TPP Database Maintenance Menu
• To exit back to the TRM Main Menu, press <F10>

(For instructions to log off the system, click this link)

-

Follow these input instructions to update spiral curve attributes:

Anchor: #i1009030Update Spiral Curve Attributes

Step

Action

Input

1

(For instructions to log onto the system, click this link)

From the TPP Database Maintenance Menu, select Update-Code 13H and press <E>; the TPP Database Maintenance Submenu appears

-

2

Input an X by Spiral Curve and press <E>; the Spiral Curve Data screen appears

-

3

Input Location Key fields

NOTE: Input only the PC or PT point for curve update

• Signed Highway System, Number, and Suffix
• From Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement
• OR To Reference Marker Number and Suffix, (+) or (–) Sign, and Displacement

4

Input remaining fields and press <E>; the system retrieves record data from TRM. A prompting message “Enter Updated Attribute Data” appears

Curve Type S

5

Input the update fields and press <F2>; the system updates the attribute and the verification message “Transaction completed successfully” appears. The original request for the current attributes to update displays for another update transaction

• Delta Angle measurements:
• Degrees, whole degree values 000 to 179
• Minutes, whole minute values 00 to 59
• Seconds, seconds to one decimal values 00.0 to 59.9
• Left/Right, direction (L or R)
• Tangent Length 1, in miles to three decimals, values 00.000 to 99.999
• Tangent Length 2, in miles to three decimals, values 00.000 to 99.999
• Curve Degree Angle measurements:
• Degrees, whole degree values 00 to 89
• Minutes, whole minute values 00 to 59
• Seconds, seconds to one decimal values 00.0 to 59.9

6

• To select Baseline Bearing, PI Curve or Normal Curve, press <F3> to exit back to the TPP Maintenance Submenu
• To input another Update-Code, press <F3> twice times to exit back to the TPP Database Maintenance Menu
• To exit back to the TRM Main Menu, press <F10>

(For instructions to log off the system, click this link)

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System Response. Because the two points which compose a normal curve also compose the second and third points of a spiral curve, the system assigns as the Curve-Id:

• 1 to the Curve Point at the TS point of the curve
• 2 to the Curve Point at the SC point of the curve
• 3 to the Curve Point at the CS point of the curve
• 4 to the Curve Point‑at the ST point of the curve.

Also, the system stores all data values with Curve Point 2.