Salvaged and/or re-galvanized guardrail on construction projects

Texas frequently uses salvaged guardrail. Any rail removed in the construction of a new highway is frequently stockpiled for use in maintenance operations. If it is damaged or rusted it is either given to the contractor to dispose of or sold as scrap. Good salvaged rail is used in repair operation or has been used to build retaining walls.
Under what circumstances will the state agency authorize its use? – It is not damaged or rusted.
How does the state agency verify and certify that the salvaged and/or re-galvanized guardrail meets state specifications? – Only that taken up from the state highway system can be reused. TxDOT does not allow contractors to supply used rail from other sources.
How long has the state agency allowed the use of salvaged and/or re-galvanized guardrail? – 30+ years.
How is salvaged and/or re-galvanized guardrail bid in a project? – It may be furnished to the contractor.
How is it documented that using salvaged and/or re-galvanized guardrail will result in significant savings? – New rail does not have to be purchased.