scope:

PURPOSE AND SCOPE

This TGN gives guidance for the generation of PLS TOWER models for use when assessing National Grid Transco (NGT) overhead line towers for re-utilisation. The guidance is intended to ensure a consistent approach is taken by any tower model originator such that models may be accepted into the NGT library of generic models for use by NGT, NGT's contractors and consultants.

This document applies to the PLS Tower modelling of all generic self supporting steel lattice transmission towers owned and operated by NGT within the UK. Once created the models can be used within PLS Cadd and PLS Tower to determine the tower's structural capacity under site specific conditions.

This guidance does not however specify how loadings are to be calculated. For application of EN50431:3-9 or BS8100 loadings, reference should be made to TS 2.4. The generic models based on this TGN will form a library of generic models held by NGT and freely available to its contractors/consultants. However, the generic models may be modified to create individual towers with site specific characteristics. These might include for example: partial metrification; partial strengthening; addition of third party assets (aerials) etc.

This guidance is not applicable to temporary masts, gantries or pole type structures.

The originator and user of the PLS Tower model shall be an experienced overhead line or tower design engineer with knowledge and experience in steel lattice structures.