<?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>0001199853</rptOwnerCik>
            <rptOwnerName>IVY JIM S</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 &amp;amp; CFO</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>17200</value></transactionShares><transactionValue><value>0</value></transactionValue><transactionAcquiredDisposedCode><value>A</value></transactionAcquiredDisposedCode></transactionAmounts><postTransactionAmounts><sharesOwnedFollowingTransaction><value>59200</value><footnoteId id="F3"/></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>91</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>91</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>9825</value></sharesOwnedFollowingTransaction></postTransactionAmounts><ownershipNature><directOrIndirectOwnership><value>I</value></directOrIndirectOwnership><natureOfOwnership><value>By Trust</value></natureOfOwnership></ownershipNature></derivativeSecurity><derivativeSecurity><securityTitle><value>Stock Option</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>36200</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>36200</value></underlyingSecurityShares></underlyingSecurity><postTransactionAmounts><sharesOwnedFollowingTransaction><value>36200</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><footnote id="F3">Balance does not include Indirect ownership of 2,523 shares held by a 401(k) Plan Trust for the benefit of the reporting person.</footnote></footnotes><ownerSignature><signatureName>Michael G. Fortado   For:  Jim S. Ivy</signatureName><signatureDate>2003-06-02</signatureDate></ownerSignature></ownershipDocument>
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X0101
4
2003-05-29
0000099780
TRINITY INDUSTRIES INC
NYSE/TRN
0001199853
IVY JIM S
0
1
0
0
Vice President &amp; CFO
Restricted Stock
2003-05-29
4
A
0
17200
0
A
59200
D
Trinity Stock Units
0
2003-05-30
4
A
0
91
17.3
A
1988-08-08
1988-08-08
Common Stock
91
9825
I
By Trust
Stock Option
17
2003-05-29
4
A
0
36200
0
A
2004-05-29
2013-05-29
Common Stock
36200
36200
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.
Balance does not include Indirect ownership of 2,523 shares held by a 401(k) Plan Trust for the benefit of the reporting person.
Michael G. Fortado   For:  Jim S. Ivy
2003-06-02