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Section 3: Delineators

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Introduction

Road delineators are retroreflective guidance devices mounted near the edge of a roadway to indicate the roadway alignment. They are typically used when changes in horizontal alignment or pavement width transitions exist. Delineators are effective aids for night driving and when either rain or snow limits the effectiveness of pavement markings.

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Delineator Design (Texas MUTCD, Section 3D.02)

Delineators consist of retroreflective material with a minimum dimension of 2.75 inches. Figure 8-4 indicates various delineator designs.

Delineators (click in image to see full-size image)

Figure 8-4. Delineators

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Delineator Application (Texas MUTCD, Section 3D.03)

Table 8-1 indicates the various uses for delineators for different types of roadways and roadway situations.

Table 8-1: Uses of Dilineators

Type of Road or Condition

Condition for Use

Delineator Spacing

Required (shall be used)

Recommended (should be used)

Optional

(may be used)

Prohibited (cannot be used)

Freeways or Expressways

Straight

D-SW on right or raised pavement

 

 

 

200-530 ft

Curve

D-SW on right

 

 

 

See Table 8-2

Ramp

D-SW (right) or D-SY (left) on one side

On outside of interchange ramp curves

 

 

 

Other than Freeways or Expressways

Straight

 

 

D-SW on right or left side

D-SY on left side of two-way roads

200-530 ft

Curve

 

 

See Table 8-2

Acceleration and Deceleration Lanes

 

D-DW or D-DY

 

 

100 ft spacing

Wrong-way

 

 

D-SR for wrong-way traffic

 

 

Pavement Narrowing (lane merge)

 

 

D-SW (right) or D-SY (left) adjacent to lane for full affected length of transition

 

 

Truck Escape Ramps

 

D-SR on both sides of ramp

 

 

50 ft spacing

Notes:

Unless indicated otherwise, the color of delineators must conform to the color of the pavement edge line on the edge line of the side of the road where the dilineators are placed.

See Table 8-2 for dilineator and barrier marker spacing on curves and the approaches to curves.

Barrier markers cannot be used to replace required dilineators.

D-SR can be mounted on the back side of existing dilineator posts.



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Delineator Placement

Typically, the height of delineators is 4-5 ft above the edge of the travel lane. Delineators are located 2-8 ft from the edge of the pavement. All delineators on a stretch of highway should be the same distance from the edge of the pavement, except where a restriction exists (such as guardrail, culvert headway, or other obstruction). Where a restriction exists, the delineators should be in line with the inner most edge of the obstruction. Figure 8-5 depicts typical delineator placement.

Typical Delineator Installation (click in image to see full-size image)

Figure 8-5. Typical Delineator Installation

When delineators are installed further than 8 ft from the edge of the pavement, it may not be practical to provide a height of 4-5 ft. In this case, the delineator is installed so the reflective unit is as close to 4.0-4.5 ft above the surface of the pavement edge as practical.

Delineators may be attached to a vertical support. An example includes along guardrail posts. Figure 8-6 illustrates examples of delineators attached to guardrail posts.

Delineator Installation on Guardrail Post (click in image to see full-size image)

Figure 8-6. Delineator Installation on Guardrail Post

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Delineation Spacing

Spacing for delineators depends on the application. Single delineators installed anywhere except along a curve or roadside barrier should be uniformly spaced 200 to 528 ft. However, when a driveway or intersection interrupts the selected spacing interval, that delineator should be located as close to its correct position without interfering with the driveway or intersection.

  • Horizontal Curves - On horizontal curves, delineator spacing should be adjusted so that several delineators are always visible to the driver. Tables 8-2 and 8-3 illustrate spacing for delineators on horizontal curves as well as on approaches and departures from horizontal curves. The minimum spacing is 20 ft, and the maximum is 300 ft.
  • Roadside Barriers - When delineators are used in conjunction with roadside barriers (i.e., guardrail, bridge rail, or concrete barrier) on straight sections of roadway, the spacing should be adjusted to ensure a minimum of three delineators are used, with a maximum spacing of 100 ft between any two delineators. When the roadside barrier is located along a curved section, Table 8-2 or 8-3 should be used to determine the appropriate delineator spacing up to a maximum of 100 ft. Section 4 should be used for applications concerning concrete median barriers.

Other types of retroreflective devices may be used on sections of roadways with guardrail, bridge rail, or concrete barrier. See Section 4 for more information.

Table 8-2: Suggested Spacing for Highway Delineators on Horizontal Curves Based on Degree of Curve

Degree of Curve

Radius of Curve, ft

Spacing in Curve (A), ft

0.5

11460

300

1

5730

225

2

2865

160

3

1910

130

4

1433

110

5

1146

100

6

955

90

7

819

85

8

716

75

9

637

75

10

573

70

11

521

65

12

478

60

13

441

60

14

409

55

15

382

55

16

358

55

19

302

50

23

249

40

29

198

35

38

151

30

57

101

20

Notes: when delineators are used on curves with a barrier, the maximum spacing between any 2 delineators is 100 ft

 (click in image to see full-size image)



Table 8-3: Suggested Spacing for Highway Delineators on Horizontal Curves Based on Advisory Speed

Advisory Speed (mph)

Spacing in Curve (A), ft

65

130

60

110

55

100

50

85

45

75

40

70

35

60 

30

55

25

50

20

40

15

35

Notes: when delineators are used on curves with a barrier, the maximum spacing between any 2 delineators is 100 ft

 (click in image to see full-size image)



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Delineation for Divided Highway Intersections and Crossovers

The following delineation is typically used for divided highway intersections and crossovers:

  • With left turn bay on approach: Use retroreflective raised pavement markers (RRPMs) to supplement the solid left turn lane line. Figure 8-7 illustrates this application. The RRPMs are placed 4 inches inside the left turn lane line and at 10 ft spacing. Use a Type II-C-R RRPM.
  • With no left turn bay on approach: Use Type 2 object marker on near side and far side of median opening. Figure 8-8 illustrates this application.

Delineation for Median Opening with Left Turn Lane on Approach (click in image to see full-size image)

Figure 8-7. Delineation for Median Opening with Left Turn Lane on Approach

 Delineation for Median Opening with No Left Turn Lane
on Approach (click in image to see full-size image)

Figure 8-8. Delineation for Median Opening with No Left Turn Lane on Approach

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