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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2014-06-30</periodOfReport>

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

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001222591</rptOwnerCik>
            <rptOwnerName>GAFFORD RONALD J</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2525 N. STEMMONS FREEWAY</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>DALLAS</rptOwnerCity>
            <rptOwnerState>TX</rptOwnerState>
            <rptOwnerZipCode>75207</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Trinity Phantom Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2014-06-30</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>81</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>43.72</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>81</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>47515</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value></value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">The Trinity Phantom Stock Units were accrued under the Trinity Industries, Inc. Deferred Plan for Directors Fees.  Stock units are converted at &quot;1 - for - 1&quot; (a rate of one stock unit per one share of Trinity common stock).  Settlement of the account will be in cash after the reporting person's retirement.</footnote>
        <footnote id="F2">On June 5, 2014, the common stock of Trinity Industries, Inc. split 2-for-1, resulting in the reporting person's ownership of 23,717 additional stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>Jared S. Richardson For:  Ronald J. Gafford</signatureName>
        <signatureDate>2014-07-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
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X0306
4
2014-06-30
0000099780
TRINITY INDUSTRIES INC
NYSE/TRN
0001222591
GAFFORD RONALD J
2525 N. STEMMONS FREEWAY
DALLAS
TX
75207
1
0
0
0
Trinity Phantom Stock Units
0
2014-06-30
4
A
0
81
43.72
A
Common Stock
81
47515
D
The Trinity Phantom Stock Units were accrued under the Trinity Industries, Inc. Deferred Plan for Directors Fees.  Stock units are converted at "1 - for - 1" (a rate of one stock unit per one share of Trinity common stock).  Settlement of the account will be in cash after the reporting person's retirement.
On June 5, 2014, the common stock of Trinity Industries, Inc. split 2-for-1, resulting in the reporting person's ownership of 23,717 additional stock units.
Jared S. Richardson For:  Ronald J. Gafford
2014-07-01