ITEM 620 - CHEVRON SIGNS
620.1 Description
This Item shall consist of furnishing and installing chevron signs in
accordance with this Specification and to the details shown on the Plans,
or as required by the Engineer.
620.2 General
620.2.1 Function
The chevron signs shall be used to guide drivers through a change in
horizontal alignment of the road such as curves and less than sharp turns.
Chevron signs shall also be used to supplement any of the advance warning
signs, the horizontal alignment signs (W-types) or the standard guide posts
and delineators.
620.2.2 Design
The chevron sign shall be a vertical rectangle. No border shall be used on
the chevron sign.
The point of the arrow or chevron shall indicate the direction of travel.
They shall be visible for at least 150 m to provide the road user with
adequate time to react to the change in alignment. The minimum lateral
offset of the chevron sign shall be 1.8 m from the edge of pavement.
The chevron signs shall be installed on the outside of the curve, set up
aligned with the approaching traffic at right angle to a driver's line of
sight. Two-sided chevron signs may be used on two-lane, two-way roads to
guide drivers travelling in both directions.
It is recommended that the spacing of the chevron signs should allow the
driver to see at least three (3) signs in view while negotiating the curve,
until the change in alignment eliminates the need for the signs.
Chevron signs shall be mounted clear of roadside vegetation and clearly
visible under headlight illumination by night. Chevrons should be installed
1.5m above the ground in the rural areas and 2.2m in the urban areas. The
recommended spacing for the chevrons within a curve are shown in Table
620.1.
Table 620.1 -Recommended Spacing for Chevron Signs
Advisory Speed Limit (kph)
|
Radius (m)
|
Chevron Spacing (m)
|
≤ 20
30-50
60-70
80-90
>90
|
≤ 60
60-120
120-210
210-300
>300
|
12
24
36
48
60
|
The above spacing distances shall apply to points within the curve.
Approach and departure spacing distances shall be twice those shown above.
620.2.3 Types of Chevron Signs
Two (2) types of chevron signs are provided for in this Item and each type
shall be used as called for on the plans. The typical sizes are shown in
Table 620.2.
Table 620.2 - Types of Chevron Signs
Type
|
Typical Size
|
Application
|
|
a.
b.
|
HM-1A
HM-1B
|
- 450mm x 600 mm
- 600mm x 800 mm
|
≤ 60 kph design speed with no visible problem
>60 kph design speed and/or with no visibility problem (e.g. fog) |
620.3 Material Requirements
620.3.1 Sign Panels
It shall conform to the requirements of Subsection 605.2.1, Sign Panels of
Item 605 - Road Sign, DPWH Standard Specifications Volume II.
620.3.2 High Performance Reflective Sheeting
The reflective sheeting shall be weather resistant and show no appreciable
cracking, blistering, crazing or dimensional change after two (2) years of
unprotected outdoor exposure.
The reflective sheeting shall have high reflectivity normal to vehicle
headlight dependent on the angle of incidence. The reflective material
shall be sharp, no glare, and directed towards the light source of approved
angle of incidence.
The reflective sheeting shall perform effectively for a minimum of seven
(7) years from date of fabrication.
The reflective sheeting must retain at least 70% of its original brightness
for regular and fluorescent sheeting respectively at the end of seven
years. All chevron signs used for the road projects should be warranted by
the sheeting manufacturer for above-stated performance.
Chevron signs shall be dated at the time of installation in order to
initiate the 7-year performance warranty. A sign-dating sticker that
indicates the manufacturer's name, material type/brand name with the month
and year of installation should be placed at the back of the sign face.
The reflective sheeting shall consist of full cube micro-prismatic lens
sheeting with an interlocking diamond seal pattern with pre-coated adhesive
backing protected by a removable liner. The minimum reflective brightness
value of reflective sheeting shall be in accordance with the following
table.
Table 620.3 - Reflective Brightness of Traffic Signs Surfaces
Observation Angle2 (degrees)
|
|||
0.2 0
|
0.5 0
|
1.0 0
|
|
| For 40 Entrance Angle1 | |||
| White
Yellow Red Green Blue |
570
425
114
57
26
|
400
300
80
40
18
|
120
90
24
12
5.4
|
| Fluorescent Yellow
Fluorescent Yellow Green Fluorescent Orange |
340
460
170
|
240
320
120
|
72
96
36
|
| For 300 Entrance Angle1 | |||
| White
Yellow Red Green Blue Fluorescent Yellow Fluorescent Yellow Green Fluorescent Orange |
215
160
43
21
10
130
170
64
|
150
112
30
15
6.8
90
120
45
|
45
34
9
4.5
2
27
36
14
|
| For 450 Entrance Angle1 | |||
| White
Yellow Red Green Blue Fluorescent Yellow Fluorescent Yellow Green Fluorescent Orange |
100
75
20
10
4.5
60
80
30
|
50
37
10
5
1.5
30
40
15
|
25
19
5
3
0.8
15
20
7
|
All units are expressed in terms of cd/lux/sq.m.
1
Entrance Angle - The angle from the illumination axis to the
retroreflector axis. The reflector axis is an axis perpendicular to the
retro-reflective surface.
2
Observation Angle - The angle between the illumination axis and observation
axis.
620.3.3. Post and Attachments
It shall conform to the applicable requirements of Subsection 605.2.3,
Posts and Frames.
Posts required for the erection of signs shall be made of galvanized steel
pipes not less than 75mm (outside diameter) x 3.25mm thick, or other
sections of equivalent strength. Aluminum alloy may be used. Plastics may
be considered, provided they have been suitably evaluated.
Attachments shall provide for the positive and robust connection of signs
to their mounting posts. Consideration shall be given to distributing
attachment loads, e.g., by the provision of suitably shaped saddles and
clamps or brackets for a round post.
620.3.4 Nuts and Bolts
It shall conform to the requirements of Subsection 605.2.4, Nuts and Bolts,
Item 605 - Road Sign, DPWH Standard Specifications, Volume II.
620.3.5 Concrete Foundation Blocks
It shall conform to the requirements of Subsection 605.2.5, Concrete
Foundation Blocks, Item 605 -Road Sign, DPWH Standard Specifications,
Volume II.
620.4 Construction Requirements
620.4.1 Excavation and Backfilling
It shall conform to the requirements of Subsection 605.3.1, Excavation and
Backfilling, Item 605 - Road Sign, DPWH Standard Specifications, Volume II.
620.4.2 Erection of Posts
It shall conform to the requirements of Subsection, 605.3.2, Erection of
Posts, Item 605 - Road Sign, DPWH Standard Specifications, Volume II.
620.4.3 Sign Panel Installation
It shall conform to the requirements of Subsection 605.3.3, Sign Panel
Installation, Item 605 - Road Sign, DPWH Standard Specifications, Volume
II.
620.5 Method of Measurement
The quantities of chevron signs shall be the number of such sign of the
size specified, including the necessary posts and supports, erected and
accepted.
620.6 Basis of Payment
The quantities measured as determined in Section 620.5, Method of
Measurement, shall be paid for at the contract unit price shown in the Bid
Schedule which price and payment shall be full compensation for furnishing
and installing chevron signs, for excavation, backfilling and construction
of foundation blocks, and all labor, equipment, tools and incidentals
necessary to complete the item.
Payment will be made under:
Pay Item Number
|
Description
|
Unit of Measurement
|
620
|
Chevron Signs
|
Each
|
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