Signfix Calculator

1. For signs not located within the jurisdiction of the Queensland Government Department of Transport and Main Roads, with the sign areas greater than 10m2 and/or in regions other than region A or region B, this design tool is not valid. Refer to AS1742.2 or to relevant State Authority guides for sign supports outside the scope of this design tool. This design tool is based on design wind speeds adopted in the Queensland Design Guide (TRUM) for road signs which have higher probability of exceedance than those derived from AS1170.
2. Footing design for cohesionless soils is based on Broms method and AS2159. Footing design for cohesive soils are designed using the method suggested by Coyle and Bierschwale, Design of Rigid Shafts in Clay for Lateral Load, ASCE J Geotech Eng, Vol 109, No 9, 1983
3. Multiple post signs are to be constructed with a minimum 1.1m spacing between the posts to comply with the frangibility testing undertaking for the Signfix system.
4. Single post sign supports must only be used where the sign attachment resists rotation as in accordance with the state Authority guidelines.
5. Design guide is based on poles with aluminium grade 6061+T6
6. Note that this estimating tool is to be used for the purposes of estimation of lightweight static signage and footing sizes only. This is an uncontrolled file and is not a certified design tool. Certification of any signage including footing sizes will remain the responsibility of the estimating tool user. Refer to Information Sheet for further information regarding Warranty

The Signfix wind charts are developed with the following assumptions as agreed with Queensland Department of Transport and Main Roads for economical and safe sign design:

1. Safe failure mode is important including design for support post yielding and bending prior to failure of the sign face and its attachment to the posts.
2. Importance Level 1 in accordance with AS/NZS 1170.0 based on “small or moderate” economic consequence and safe failure model with failure unlikely to endanger human life. A design working life of 25 years is considered and an annual probability of exceedance of 1 in 100 (1/100) for cyclonic and non-cyclonic wind speeds.
3. Design spreadsheet has been developed for Region A, Region B1, Region B2, Region C and Region D
4. Design calculation assumes a topographic multiplier of 1. For exposed locations or where the failure of the post is deemed to be more hazardous to road users, we recommend selection of the next post size higher to account for higher wind speeds or use an additional pole.
5. Pressures are designed based on a Cshp from Section B.2 with AS/NZS 1170.2 for “Freestanding hoardings and walls” (with exceptions as per notes 6 and 7)
6. A pressure reduction factor R = 0.5 is applied to the ultimate support post design pressure derived in accordance with AS/NZS 1170.2. This factor is applied to the resultant pressure derived from wind speed and pressure co-efficient.
7. Effective design eccentricity is taken as e = 0.1b resulting in a 33% increase in force on the windward post. This eccentricity is less than the e = 0.2b nominated in AS/NZS 1170.2 for winds at 45 degrees on the basis that a reduced eccentricity assumption is valid for very flexible sign support structures that will distribute uneven loads.