<?xml version="1.0"?>
<ownershipDocument>
    <schemaVersion>X0101</schemaVersion>

    <documentType>4</documentType><periodOfReport>2003-05-29</periodOfReport>
    <issuer>
        <issuerCik>0000099780</issuerCik>
        <issuerName>TRINITY INDUSTRIES INC</issuerName>
        <issuerTradingSymbol>NYSE/TRN</issuerTradingSymbol></issuer><reportingOwner><reportingOwnerId>
            <rptOwnerCik>0001199854</rptOwnerCik>
            <rptOwnerName>LEE JOHN M</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>  </rptOwnerStreet1>
            <rptOwnerStreet2>  </rptOwnerStreet2>
            <rptOwnerCity>  </rptOwnerCity>
            <rptOwnerState>  </rptOwnerState>
            <rptOwnerZipCode>  </rptOwnerZipCode>
        </reportingOwnerAddress>
            <reportingOwnerRelationship>
<isDirector>0</isDirector><isOfficer>1</isOfficer><isTenPercentOwner>0</isTenPercentOwner><isOther>0</isOther><officerTitle>Vice President</officerTitle></reportingOwnerRelationship></reportingOwner><nonDerivativeSecurity><securityTitle><value>Restricted Stock</value></securityTitle><transactionDate><value>2003-05-29</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>3780</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>21669</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></nonDerivativeSecurity><derivativeSecurity><securityTitle><value>Trinity Stock Units</value></securityTitle><conversionOrExercisePrice><value>0</value><footnoteId id="F1"/></conversionOrExercisePrice><transactionDate><value>2003-05-30</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>4</value></transactionShares><transactionValue><value>17.3</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>1988-08-08</value><footnoteId id="F1"/></exerciseDate><expirationDate><value>1988-08-08</value><footnoteId id="F1"/></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>4</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>1436</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>by Trust</value></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Stock Option (right to buy)</value></securityTitle><conversionOrExercisePrice><value>17</value></conversionOrExercisePrice><transactionDate><value>2003-05-29</value></transactionDate><transactionCoding><transactionFormType>4</transactionFormType><transactionCode>A</transactionCode><equitySwapInvolved>0</equitySwapInvolved></transactionCoding><transactionAmounts><transactionShares><value>8010</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><exerciseDate><value>2004-05-29</value><footnoteId id="F2"/></exerciseDate><expirationDate><value>2013-05-29</value></expirationDate><underlyingSecurity><underlyingSecurityTitle><value>Common Stock</value></underlyingSecurityTitle><underlyingSecurityShares><value>8010</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>8010</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>D</value></directOrIndirectOwnership><natureOfOwnership><value></value></natureOfOwnership></ownershipNature></derivativeSecurity><footnotes><footnote id="F1">The Trinity Stock Units were accrued under the Trinity Industries, Inc. Supplemental Profit Sharing Plan and will be settled upon the reporting  person's retirement or other termination of service or earlier for in service distributions under limited circumstances as provided by the plan.  Stock Units convert at a ratio of 1 to 1.  The data in columns  2 and 6 are for filing format purposes only.</footnote><footnote id="F2">Option Term is Ten Years.  Options vest over 5 years at twenty percent (20%) per year beginning on the first anniversary of the grant date.</footnote></footnotes><ownerSignature><signatureName>Michael G. Fortado  For:  John M. Lee</signatureName><signatureDate>2003-06-02</signatureDate></ownerSignature></ownershipDocument>
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X0101
4
2003-05-29
0000099780
TRINITY INDUSTRIES INC
NYSE/TRN
0001199854
LEE JOHN M
0
1
0
0
Vice President
Restricted Stock
2003-05-29
4
A
0
3780
0
A
21669
D
Trinity Stock Units
0
2003-05-30
4
A
0
4
17.3
A
1988-08-08
1988-08-08
Common Stock
4
1436
I
by Trust
Stock Option (right to buy)
17
2003-05-29
4
A
0
8010
0
A
2004-05-29
2013-05-29
Common Stock
8010
8010
D
The Trinity Stock Units were accrued under the Trinity Industries, Inc. Supplemental Profit Sharing Plan and will be settled upon the reporting  person's retirement or other termination of service or earlier for in service distributions under limited circumstances as provided by the plan.  Stock Units convert at a ratio of 1 to 1.  The data in columns  2 and 6 are for filing format purposes only.
Option Term is Ten Years.  Options vest over 5 years at twenty percent (20%) per year beginning on the first anniversary of the grant date.
Michael G. Fortado  For:  John M. Lee
2003-06-02