<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2018-05-07</periodOfReport>

    <issuer>
        <issuerCik>0000099780</issuerCik>
        <issuerName>TRINITY INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>NYSE/TRN</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001289486</rptOwnerCik>
            <rptOwnerName>Lovett Melendy E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2525 STEMMONS FREEWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75207</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>SVP &amp; Chief Admin Officer</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>30000</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>93079</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2018-05-07</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>7932</value>
                    <footnoteId id="F2"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>101011</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Restricted Stock Units granted pursuant to the Fourth Amended and Restated Trinity Industries, Inc. 2004 Stock Option and Incentive Plan.  Distribution is 1 for 1 in Trinity Stock after shares vest 1/3 per year on May 15, 2021, 2022, and 2023.</footnote>
        <footnote id="F2">Restricted Stock Units granted pursuant to the Fourth Amended and Restated Trinity Industries, Inc. 2004 Stock Option and Incentive Plan.  Distribution is 1 for 1 in Trinity Stock after shares vest 50% on May 15, 2021 and 50% on May 15, 2022.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Mary E. Henderson  For: Melendy E. Lovett</signatureName>
        <signatureDate>2018-05-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2018-05-07
0000099780
TRINITY INDUSTRIES INC
NYSE/TRN
0001289486
Lovett Melendy E
2525 STEMMONS FREEWAY
DALLAS
TX
75207
0
1
0
0
SVP & Chief Admin Officer
Common Stock
2018-05-07
4
A
0
30000
0
A
93079
D
Common Stock
2018-05-07
4
A
0
7932
0
A
101011
D
Restricted Stock Units granted pursuant to the Fourth Amended and Restated Trinity Industries, Inc. 2004 Stock Option and Incentive Plan.  Distribution is 1 for 1 in Trinity Stock after shares vest 1/3 per year on May 15, 2021, 2022, and 2023.
Restricted Stock Units granted pursuant to the Fourth Amended and Restated Trinity Industries, Inc. 2004 Stock Option and Incentive Plan.  Distribution is 1 for 1 in Trinity Stock after shares vest 50% on May 15, 2021 and 50% on May 15, 2022.
Mary E. Henderson  For: Melendy E. Lovett
2018-05-09