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Traffic Engineering Manual Vol 2, Chapter 6 - Edition 3, December 2001

Chapter 6

Side Mounted Signs:Installation


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AMENDMENT RECORD

Ed/Rev No Page(s) Issue Date Amendment Description

Ed 1 All July 1986 Original Manual

Ed 2 All April 2000 Initial draft for comment(VicRoads only)

Ed 3 All December 2001 New Edition

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Contents

6.1 PROCEDURE FOR DETERMINING POST AND FITTINGSREQUIREMENTS ........................................................................... 6-5

6.2 POST SELECTION ........................................................................ 6-7

6.2.1 Number and Spacing of Posts ............................................ 6-7

6.2.2 Post Type and Size ............................................................. 6-7

6.2.3 Determination of Post Length ........................................... 6-12

6.3 FITTINGS SELECTION................................................................ 6-13

6.4 SPECIAL PROCEDURES ............................................................ 6-15

6.4.1 Posts in Sockets .............................................................. 6-15

6.4.2 Single Post Mounting for Large Signs ............................... 6-15

6.4.3 Joint-use Supports for Side Mounted Signs ..................... 6-16

6.5 COLOUR OF SIGN SUPPORTS .................................................. 6-19

APPENDIX 6AINSTALLATION OF STRUTTED ALUMINIUM SIGN POSTS ................ 6-21

APPENDIX 6BDESIGN STANDARDS FOR SINGLE POST MOUNTING OFLARGE SIGNS ........................................................................................ 6-27


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To determine the required posts and fittings for a side-mounted sign, proceedas follows:

■ Locate the sign precisely, both laterally and longitudinally, see Sections 5.2and 5.4, and obtain ground levels under the sign relative to the nearest edgeof carriageway,

■ Determine the mounting height relative to the carriageway edge, see Section5.3, and calculate the height of sign above ground level,

■ Determine the number of posts required; see Section 6.2.1, noting that up tofour posts may be used for very wide signs,

■ Determine the post type and size required, see Section 6.2.2,

■ Calculate the overall length of post required, see Section 6.2.3, alsoSection 2.5,

■ Determine the type and number of fittings required, see Section 6.3.

Note also that special procedures, see Section 6.4, are applicable in certaincases.


6.1ProcedureforDeterminingPost andFittingsRequirements


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6.2.1 Number and Spacing of Posts

The number of posts used to mount signs is as follows:

■ Single Post Mounting

❑ square or rectangular signs up to 900 mm wide,

❑ diamond signs with side dimension up to 900 mm (ie. C size).

See also Section 6.4.2 regarding single post supports for large signs.

■ Two Post Mounting

❑ all signs wider than 900 mm or a C size diamond sign, except as notedbelow, or in Section 6.4.2.

The spacing of posts is desirably 0.6 times the sign width.

■ Three Post Mounting

❑ acceptable alternative to two posts mounting for signs 3.65 m or wider.

The spacing is 0.45 times the sign width (1.6 m minimum).

Note that for wide signs it will frequently be more economical and less hazardousto use three posts of smaller cross-section than two larger posts.

■ Four Post Mounting

❑ applicable only to very wide signs, 4.5 m or wider. The minimum postspacing should be 1.3 m.

6.2.2 Post Type and Size

Details of standard post types and sizes, and the purposes for which each isused, are given in Table 6.1.

To determine the size and type of post required, refer to Figure 6.1. Post typesshown to the left of the graph may be used wherever the sign is in a protectedposition, ie. behind guard fence, on a cut batter where permitted in Section 5.2,or elsewhere where it is unlikely to be struck by an out-of-control vehicle. Forsigns in exposed positions, the types shown to the right of the graph should beused.

Frangible hardwood posts and slip base strutted aluminium posts are illustratedin Figures 6.2 and 6.3 respectively. The method of installation of struttedaluminium posts is given in Appendix 6A. In order that the posts perform asintended when struck by an errant vehicle, the installation must be carried outin accordance with Appendix 6A.


6.2PostSelection


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TABLE 6.1: STANDARD SIGN POST TYPES AND USES

Notes to Table 6.1:

1. Depths may need to be increased in soft ground to ensure post stability.

2. Galvanised steel tube used for sign posts is to be made from C350 grade steel.

Tube sizes are specified by nominal bore (NB) and wall thickness, both in mm.

Figure 6.1 assumes tube wall thickness as noted in the above table. However, lightergauge 50 NB tube, with 2.3 mm wall thickness, may be used to support signs of area upto 0.8 sq.m per post at sign centroid heights of up to 2.2 m. This tube will thus besuitable for single post mounting of small signs, and for multiple post mounting of widerbut relatively shallow signs such as intersection direction signs.

3. Posts of 50 mm nom. bore or less are not breakaway types, but are considered lightenough to present minimal hazard to out-of-control vehicles.

4. Timber or aluminium frangible posts are generally not appropriate for use in urban areas(freeway main carriageways and ramps excepted) where roadside space is restrictiveand pedestrian activity exists. As far as practicable, steel posts up to 100 mm nom.bore should be used in lieu. In especially vulnerable locations post size is desirablylimited to 80 mm.

5. Requires special procedure for determining post and strut length, see Appendix 6A.

6. Galvanised square tube, of equivalent strength to the circular tube sizes shown in theabove table, may be used as an alternative type of sign post.

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FIGURE 6.1: SIGN POST SELECTION GUIDE(ALL DIMENSIONS IN MILLIMETRES UNLESS OTHERWISE SHOWN)

Notes to Figure 6.1:

1. Dimension H and H1 relate to ground surface below sign.

On uneven ground, H = height of the longest post.

2. For 3 post mounting conditions, see Section 6.2.1.

3. See Note (4) to Table 6.1 regarding use of frangible posts in urban areas.


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FIGURE 6.2: 180 X 100 MM FRANGIBLE HARDWOOD SIGN POST(ALL DIMENSIONS IN MILLIMETRES UNLESS OTHERWISE SHOWN)

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FIGURE 6.3: SLIP BASE STRUTTED ALUMINIUM SIGN POST(ALL DIMENSIONS IN MILLIMETRES UNLESS OTHERWISE SHOWN)

Detailed instruction for the installation of these posts is given at Appendix 6A


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6.2.3 Determination of Post Length

The length of post required comprises the sum of:

■ the signboard depth less 50 mm (clearance at top of sign),

■ the mounting height, adjusted for difference between pavement level andground level at base of post, and

■ depth of post into the ground, Table 6.1.

Where applicable, a standard length should be selected from Table 6.1, whichretains the above dimensions within their permissible ranges. If this is notpracticable a special length may need to be ordered. Timber posts and thelarger sizes of steel and aluminium posts are ordered to the exact desiredlength.

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Examples of sign post fittings and their uses are shown in Figure 6.4.

Some of the fittings illustrated in Figure 6.4 are proprietary designs. Otherfittings that have the same performance may be substituted for them.

FIGURE 6.4: SIGN POST FITTINGS


6.3FittingsSelection


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To select the type and number of fittings required:

■ Determine whether the sign will be stiffened on the back with “Unistrut” channelor similar. In general, the following permanent sign blanks are stiffened:

❑ Rectangular, square and octagonal signs wider than 700 mm,

❑ Diamond warning signs 750 x 750 mm and larger,

❑ Triangular signs wider than 750 mm,

However, 1800 x 300 mm hazard markers are not stiffened,

■ Determine whether back to back mounting of two signs is required,

■ Taking account of the type and size of post to be used, select an appropriatefitting from Figure 6.4,

■ Taking into account that for stiffened signs, one fitting is required at eachintercept point of post and horizontal stiffening section, determine the numberof fittings required for each separate sign on the basis of:

❑ One fitting per post for signs up to 200 mm in depth,

❑ Two fittings per post for signs 201 to 900 mm in depth,

❑ Three fittings per post for signs 901 to 1200 mm in depth,

❑ One extra fitting per post for each 400 mm increment or part thereofabove 1200 mm.

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6.4.1 Posts in Sockets

Where a sign is to be erected in paved areas or in a location where it could beexpected to be struck from time to time by vehicles, eg. on an urban medianend; or where it may need to be removed occasionally to accommodate theswept path of overdimensional vehicles when turning, the post should be insertedinto a socket cast into the ground. Suitable socket sizes for posts are asfollows.

The socket should be set into the ground to the same depth as the post wouldotherwise have been set and should protrude approximately 50 mm above anearth surface, or 25 mm above a concrete or bitumen surface.

The socket may be blocked off so that the sign post penetrates a minimum of450 mm into the socket. The sign post should be securely fixed into the socketby an approved vandal proof method.


6.4SpecialProcedures

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6.4.2 Single Post Mounting for Large Signs

The mounting of large signs on two posts in some locations in urban areas, forexample, above a footpath, may present a problem in that the structure may beaesthetically displeasing, or one of the posts may be an obstruction to pedestriansor otherwise difficult to site.

Designs for standardised single post, side mounted sign structures utilising114 mm, 140 mm or 165 mm OD galvanised steel posts are provided inAppendix 6B. The designs are suitable for mounting heights (ground to loweredge of sign) up to about 2.6 m, and subject to certain signboard shape limitations(width/depth ratio) the post may be offset by up to 400 mm from the edge of thesign. Typical maximum signboard sizes which may be mounted this way on a165 mm post can be estimated from Figure 6.5 for post offsets of 0 and 1 m.

Such supports will, however, be more costly than conventional two-post mounting,and are not to be made as breakaway supports.

FIGURE 6.5: MAXIMUM SIGN BOARD SIZES ONSTANDARD SINGLE POST SUPPORTS

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6.4.3 Joint-use Supports for Side Mounted Signs

Wherever practicable in urban areas, existing roadside poles, lighting columns,traffic signal pedestals, etc. should be used for the mounting of signs to reduceas much as possible any unsightly proliferation of poles in the environment.

Small signs, generally not more than 0.3 sq.m in area, may be attached toelectricity distribution poles, tramway poles, lighting columns and signalpedestals or mast arms by banding to steel or concrete columns.

Larger signs may require that the pole be checked structurally for the addedloading of the sign, or may require the design of special joint-use supports. Thelatter will normally apply where traffic signal pedestals are to be used. Largesigns will rarely be permitted on electricity distribution poles. In most cases,larger signs will need specially designed attachments for fitting the sign to thepole. The assistance of an experienced traffic engineer should be sought inlocating signs most advantageously in such cases, and a structural engineershould be consulted where special structures or attachments, or checks onexisting structures, are required.

Typical maximum signboard areas which may be attached to joint-use structuresare as follows:

Standard 114 mm OD signal pedestal - 1.0 sq.m

Special 165 mm OD signal pedestals - 2.7 sq.m

(Installed only by special arrangement with VicRoads' Signal Installation& Maintenance Section)

Joint use traffic signal/lighting column or traffic signal mast arm -1.6 sq.m less the area of any traffic signal target boards facing in thesame direction.

When contemplating the use of joint-use supports for signs it is necessary toensure that:

■ the function of the sign is not adversely affected by relocating it on a joint-use support,

■ all required lateral and vertical clearances are provided, see Sections 5.2and 5.3,

■ permission is obtained for use of structures which are not VicRoads property.

See also Section 7.4.8 regarding joint-use structures for overhead signs.


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6.5Colour ofSignSupports

Sign supports are normally left unpainted, except as follows:

■ Sign supports on declared roads (along with traffic signal pedestals) may bepainted where requested by Councils or developers provided that they agreeto meet all associated costs, including maintenance. This is conditional uponthe Council/developer entering into an agreement to reinstate the poles totheir original condition in the event that the Council/developer discontinuesits own colour scheme,

■ In isolated situations (ie. where painting of sign supports has not beeninitiated), posts may need to be painted in order to reduce any undesirableaesthetic effects using an approved neutral colour (eg. at channelisedintersections),

■ Unless galvanised, large diameter steel posts and all overhead or high mountedsign structures are either painted an approved neutral colour or finished witha zinc-in-silicate coating,

■ If it is necessary to use timber posts for large direction or similar signs inurban areas, they may be painted an approved neutral colour on aestheticgrounds.


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INSTALLATION OF STRUTTED ALUMINIUM SIGN POSTS

6A.1 GENERAL

Guides for the use of strutted aluminium sign posts are given in Section 6.2.2(or alternatively Table 6.1). Post requirements in terms of signboard area andmounting height can be determined from Figure 6.1.

This appendix gives a series of suggested steps for laying out the installationsite, installing the footings and erecting the sign posts.

6A.2 SITE LAYOUT

Having determined the precise sign location, longitudinally and laterally, andwhether two or three posts will be required, proceed as follows:

Step 1

Locate and peg the positions of the vertical posts, and run a set-out line backfrom each at 90o to the line of the posts, see Figure 6A.1.

Post spacing S is obtained from Section 6.2.1. The angle 0 is required to avoidspecular reflection, see Section 5.5, and should be 5o when the sign is locatedon a straight or left hand curve or zero on a right hand curve. Note that 5o isequivalent to an offset of the outer edge of sign of approximately 100 mm permetre of sign width.

FIGURE 6A.1: SETTING OUT VERTICAL POST POSITIONS

Appendix 6A


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Step 2

Considering firstly the shortest post:

(a) Signs on Substantially Level Ground or Fill Batters

The mounting height U (Figure 6A.2) measured from the top of the footing,should be a minimum of 2200 mm. On a fill batter this may need to be increasedwhere the mounting height to lower edge of sign would otherwise fall below therequired minimum of 1500 mm above nearest edge of pavement (or 2000 whereit is desired for uniformity of height with other large signs in the vicinity).

(b) Signs on Steep Cut Batters

On cut batter slopes 2:1 or steeper the minimum mounting height of 2200 mmmay be reduced providing:

■ the lowest corner of the sign is a minimum of 800 mm above the ground,and,

■ the mounting height of any post within 1.2 m vertically of toe of batter is aminimum of 2200 mm.

Run levels back along the set-out line, so that the natural surface slope can beestablished, and the location of the strut footing can be determined in accordancewith the geometry illustrated in Figure 6A.2, where:

H = height of signboard,

C = footing clearance above natural surface, which must lie between 50and 125 mm,

X = ground slope along set-out line,

OS = horizontal distance between post and strut footings, and

V = level difference between post and strut footings(negative if strut footing is below post footing),

0 = Strut Angle (see 6A.4).

FIGURE 6A.2: ESTABLISHING STRUT FOOTING POSITIONS

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Step 3

Obtain levels for the top of second (and third) vertical post footing(s) andcalculate the length U for the remaining post(s). Repeat Step 2 for the remainingpost(s).

Step 4

From Figure 6A.3, determine the length of each vertical post (P) and strut (D),and after checking strut length, see 6A.3 CHECKING STRUT LENGTH below,order components accordingly.

Complete post assemblies are supplied in kit form, one kit for each post. Notethat vertical posts and struts will be provided slightly overlength with the finalpop-rivetted attachment of one strut end to be made in the field after checkingand cutting the post or strut to exact length on site.

FIGURE 6A.3: CALCULATION OF POST AND STRUT LENGTHSAND ASSEMBLY GEOMETRY


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6A.3 CHECKING STRUT LENGTH

After calculation of strut lengths as in Step 4 above, each should be checkedfor structural adequacy against Figure 6A.4. If one or more struts fail thischeck, either:

■ the sign should be relocated to a position allowing shorter struts to be used,

■ an additional post may be necessary, provided the requirements ofSection 6.2.1 can be met, or,

■ an alternative mounting system may be necessary, eg. rigid posts protectedby guardfence.

FIGURE 6A.4: ALLOWABLE STRUT LENGTHS

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6A.4 ALTERNATIVE STRUT ANGLES

The strut angle should wherever practicable be 45o. If due to site conditions asmaller strut angle is required, it may be reduced to not less than 30o.

6A.5 POST ASSEMBLY AND ERECTION

Post and strut footings should be installed such that the height is within therange 50 to 125 mm above ground level and varies by not more than 25 mmfrom the clearance C adopted for calculation in Steps 2 and 3 of 6A.2 SITELAYOUT.

Each footing is concreted into a hole approximately 400 mm dia. x 1200 mmdeep.

Installation of each post and strut assembly is then carried out in accordancewith Figure 6A.5.


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FIGURE 6A.5: POST ASSEMBLY AND ERECTION

Notes to Figure 6A.5:

As a final test, when sign construction is complete, it is critical that the strut assemblies beshaken to ensure that no movement exists in any footings.

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DESIGN STANDARDS FOR SINGLE POST MOUNTING OF LARGESIGNS

6B.1 GENERAL

The following charts are used to determine whether a sign can be mounted ona single post utilising 114 mm, 140 mm or 165 mm OD galvanised steel posts.

6B.2 POST SIZE SELECTION PROCEDURE

With reference to Figure 6B.1:

1. Determine the area of the sign (A x B) and mounting height "H1".

2. Determine offset "S" and select the appropriate Figure 6B.2, 6B.3, or 6B.4,rounding up to the next whole number offset.

3. Determine the post size by projecting horizontal and vertical lines knowingmounting height and sign area. The post size required is the one above theintercept point.

Appendix 6B

FIGURE 6B.1: TYPICAL SINGLE POST MOUNTING ARRANGEMENT

6B.3 CHANNEL SIZE SELECTION PROCEDURE

Single post mounted signs require larger horizontal sign stiffening sections asthese signs are cantilevered.

1. Determine the outreach, which is the horizontal distance from the centre ofthe post to the furthest edge of the sign.

2. Knowing the sign depth "B", determine from Figure 6B.5 the number andsize of stiffening sections required.

Upon erection of the sign, the 41 mm x 41 mm channel section transport bracingshall be retained, but cut to provide 50 mm clearance inside the top and bottomedges of the sign.

6B.4 MAXIMUM SIGN AREA AND TYPICAL DRAWING

Table 6B.1 tabulates the maximum sign areas that can be supported for variouspost sizes taking into account the mounting height and offset mountingarrangement.

Figures 6B.6-6B.9 show typical sign manufacturing drawings that include detailsof horizontal stiffening sections and transport bracing. Also included are standarddrawings for General Arrangement, Sign Mounting Brackets and Post and Footingdetails.


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FIGURE 6B.2 - POST SIZE SELECTION

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FIGURE 6B.5 - CHANNEL SIZE SELECTION


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5.1 63.11 63.01 49.6 75.8 05.7 30.5 15.5 65.4 60.3

0.2 15.9 68.8 53.6 50.7 73.6 75.4 34.4 58.3 77.2

5.2 90.8 56.7 97.5 29.5 84.5 61.4 66.3 92.3 05.2

0.3 89.6 86.6 82.5 60.5 67.4 87.3 80.3 48.2 62.2

5.3 01.6 88.5 28.4 93.4 71.4 44.3 46.2 74.2 40.2

0.4 83.5 22.5 14.4 48.3 96.3 31.3 82.2 71.2 58.1

5.4 87.4 66.4 40.4 93.3 82.3 58.2 99.1 19.1 76.1

TABLE 6B.1 - MAXIMUM SIGN AREA FOR SINGLE POST SUPPORTSIGNS (M 2)

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FIGURE 6B.6 - TYPICAL SIGN FACE DESIGN DETAIL FORSINGLE POST MOUNTED SUPPORT


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FIGURE 6B.7 - STANDARD SINGLE POST SIGN SUPPORTGENERAL ARRANGEMENT

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FIGURE 6B.8 - STANDARD SINGLE POST SIGN SUPPORTSIGN MOUNTING BRACKETS


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FIGURE 6B.9 - STANDARD SINGLE POST SIGN SUPPORTPOST AND FOOTINGS

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