Exhibit 10(a)

THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT
AND REAFFIRMATION OF GUARANTIES

This
THIRD AMENDMENT TO AMENDED AND RESTATED CREDIT AGREEMENT AND REAFFIRMATION OF GUARANTIES, dated as of November 7, 2007 (the "Third
Amendment"), is entered into by and between Quixote Corporation, a Delaware corporation (the "Borrower"), whose address is 35
East Wacker Drive, Chicago, Illinois 60601, and Quixote Transportation Safety, Inc., Transafe Corporation, Energy Absorption Systems, Inc., Energy Absorption Systems (AL) LLC, Surface
Systems, Inc., Nu-Metrics, Inc., Highway Information Systems, Inc., U.S. Traffic Corporation (formerly known as Green Light Acquisition Corporation) and Peek Traffic
Corporation, (formerly known as Vision Acquisition Corporation), as Subsidiary Guarantors, (each being referred to herein as a "Guarantor" and
collectively referred to herein as the "Guarantors"), and LaSalle Bank National Association, a national banking association (the
"Bank"), whose address is 135 South LaSalle Street, Chicago, Illinois 60603.

R E C I T A L S:

A.    The
Borrower and the Bank entered into that certain Amended and Restated Credit Agreement, dated as of April 20, 2005 (the "Original Credit
Agreement"), as amended by that certain First Amendment to Amended and Restated Credit Agreement and Reaffirmation of Guaranties dated as of December 1, 2006, (the
"First Amendment") and that certain Second Amendment to Amended and Restated Credit Agreement and Reaffirmation of Guaranties dated as of
March 15, 2007 (the "Second Amendment" and together with the Original Credit Agreement and the First Amendment, the
"Credit Agreement") pursuant to which Credit Agreement the Bank has made a Revolving Loan to the Borrower evidenced by that certain Revolving Loan Note,
dated as of March 15, 2007, in the maximum principal amount of $30,000,000, executed by Borrower and made payable to the order of the Bank (the "Revolving
Note").

B.    In
connection with the Original Credit Agreement, the Guarantors executed and delivered to the Bank that certain Guaranty dated as of May 16, 2003 in favor of the
Bank, as amended by that Reaffirmation and Amendment of Subsidiary Guaranty dated as of April 20, 2005 (the "Guaranty").

C.    At
the present time the Borrower and the Guarantors request, and the Bank is agreeable to, the modification of certain terms contained in the Credit Agreement as set
forth herein, all pursuant to the terms and conditions hereinafter set forth.

NOW
THEREFORE, in consideration of the premises and other good and valuable consideration, the receipt and adequacy of which are hereby acknowledged, the Borrower, the Guarantors and the
Bank hereby agree as follows:

A G R E E M E N T S:

1.RECITALS.The foregoing Recitals are hereby made a part of this Third Amendment.

2.DEFINITIONS.Capitalized words and phrases used herein without definition shall have the respective meanings
ascribed thereto in the Credit Agreement.

3.AMENDMENTS TO THE CREDIT AGREEMENT.



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|Level |  | Senior
Leverage
Ratio |  | Eurodollar
Margin/L/C Fee
Percentage |  | ABR
Margin |  | Commitment
Fee
Percentage
|----- |  | --------------------- |  | ------------------------------------ |  | ---------- |  | -------------------------
|V     |  | >2.50                 |  | 2.25%                                |  | 0%         |  | 0.375%                   
|IV    |  | >2.00 BUT 32.50       |  | 2.00%                                |  | 0%         |  | 0.250%                   
|III   |  | >1.50 BUT 32.00       |  | 1.75%                                |  | 0%         |  | 0.250%                   
|II    |  | >1.00 BUT 31.50       |  | 1.50%                                |  | 0%         |  | 0.250%                   
|I     |  | £1.00                 |  | 1.25%                                |  | 0%         |  | 0.250%                   



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4.WAIVER.The Bank hereby waives the following Defaults under the Credit Agreement:



The
foregoing waivers shall not be construed or deemed to be a waiver by Bank of any other Defaults by Borrower whether known or undiscovered.

5.REAFFIRMATION OF GUARANTIES.Each of the Guarantors hereby expressly (a) consents to the execution by
the Borrower and the Bank of this Third Amendment, (b) acknowledges that the "Guaranteed Debt" (as defined in each of the Guaranties) includes all of the obligations and liabilities owing from
the Borrower to the Bank, including, but not limited to, the obligations and liabilities of the Borrower to the Bank under and pursuant to the Credit Agreement, as amended from time to time, and as
evidenced by the Revolving Note, as modified, extended and/or replaced from time to time, (c) reaffirms, assumes and binds themselves in all respects to all of the obligations, liabilities,
duties, covenants, terms and conditions that are contained in their respective Guaranty, (d) agrees that all such obligations and liabilities under their respective Guaranty shall continue in
full force and effect and shall not be discharged, limited, impaired or affected in any manner whatsoever, and (e) represents and warrants that each of the representations and warranties made
by such Guarantor in any of the documents executed in connection with the Loans remain true and correct as of the date hereof.

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6.REPRESENTATIONS AND WARRANTIES.To induce the Bank to enter into this Third Amendment, the Borrower and each
Guarantor hereby certifies, represents and warrants to the Bank that:



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7.CONDITIONS PRECEDENT.This Third Amendment shall become effective as of the date above first written after
receipt by the Bank of the following documents:



8.GENERAL.



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[Signatures
on following page]

7

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IN
WITNESS WHEREOF, the parties hereto have executed this Third Amendment to the Amended and Restated Credit Agreement and Reaffirmation of Guaranties as of the date first above written.

| |  | QUIXOTE CORPORATION,
a Delaware corporation, as Borrower                                                                                                                                                                                              
| |  | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| |  | By:                                                                                                                                                                                                                                                   
| |  | Name:                                                                                                                                                                                                                                                 
| |  | Title:                                                                                                                                                                                                                                                
| |  | QUIXOTE TRANSPORTATION SAFETY, INC.
TRANSAFE CORPORATION
ENERGY ABSORPTION SYSTEMS, INC.
ENERGY ABSORPTION SYSTEMS (AL) LLC
SURFACE SYSTEMS, INC.
NU-METRICS, INC.
HIGHWAY INFORMATION SYSTEMS, INC.
U.S. TRAFFIC CORPORATION
PEEK TRAFFIC CORPORATION
| |  | By:                                                                                                                                                                                                                                                   
| |  | Name:                                                                                                                                                                                                                                                 
| |  | Title:                                                                                                                                                                                                                                                
| |  |                                                                                                                                                                                                                                                       
| |  | LASALLE BANK NATIONAL ASSOCIATION, a
national banking association                                                                                                                                                                                     
| |  | By:                                                                                                                                                                                                                                                   
| |  | Name:                                                                                                                                                                                                                                                 
| |  | Title:                                                                                                                                                                                                                                                

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Exhibit A

AMENDED AND RESTATED REVOLVING LOAN NOTE

|$40,000,000 |  | Chicago, Illinois
November 7, 2007
|----------- |  | ----------------------------------

FOR VALUE RECEIVED, the undersigned, QUIXOTE CORPORATION, a Delaware corporation (the "Borrower"), promises to pay
to the order of LaSalle Bank National Association and its registered assigns (the "Lender"), on February 1, 2010, the principal sum of Forty
Million and No/100 Dollars ($40,000,000.00), or, if less, the aggregate unpaid principal amount of all loans made by the Lender to the Borrower from time to time pursuant to that certain Amended and
Restated Credit Agreement, dated as of April 20, 2005, between the Borrower and Lender as amended by the First Amendment to Amended and Restated Credit Agreement and Reaffirmation of
Guaranties, dated as of December 1, 2006, that certain Second Amendment to Amended and Restated Credit Agreement and Reaffirmation of Guaranties, dated as of March 15, 2007, and that
certain Third Amendment to Amended and Restated Credit Agreement and Reaffirmation of Guaranties as of the date hereof (together with all amendments, if any, from time to time made thereto, the
"Credit Agreement").

The
Borrower agrees to pay interest on the principal hereof remaining from time to time unpaid in accordance with Section 2.13 of the Credit Agreement.

All
payments of principal and interest on this Note shall be payable in lawful currency of the United States of America at the Agent's office at 135 South LaSalle Street, Chicago,
Illinois 60603, in immediately available funds.

This
Note evidences indebtedness incurred under, and is subject to the terms and provisions of, the Credit Agreement, to which reference is made for a statement of those terms and
provisions. Should the indebtedness represented by this Note or any part hereof be collected at law or in equity or in bankruptcy, receivership, or other court proceedings, or this Note be placed in
the hands of attorneys for collection after maturity (by declaration or otherwise), the undersigned agrees to pay, in addition to principal and interest due and payable hereon, reasonable attorneys'
and collection fees.

This
Note constitutes a renewal and restatement of, and replacement and substitution for, that certain Revolving Note, dated as of March 15, 2007 in the maximum principal amount
of Thirty Million and 00/100 Dollars ($30,000,000.00), executed by the Borrower and made payable to the order of the Bank (the "Prior Note"). The
indebtedness evidenced by the Prior Note is continuing indebtedness evidenced hereby, and nothing herein shall be deemed to constitute a payment, settlement or novation of the Prior Note, or to
release or otherwise adversely affect any lien, mortgage or security interest securing such indebtedness or any rights of the Bank against any guarantor, surety or other party primarily or secondarily
liable for such indebtedness.

[Signature
on following page]

A-1

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IN
WITNESS WHEREOF, the Borrower has executed this Note as of the date first above written

| |  | QUIXOTE CORPORATION
| |  | -------------------
| |  | By:                
| |  |                    
| |  | Name               
| |  |                    
| |  | Title:             
| |  |                    

A-2

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Loans made by LASALLE BANK NATIONAL ASSOCIATION (the "Lender") to QUIXOTE CORPORATION (the "Borrower")
under the Amended and Restated Credit Agreement, dated as of April 20, 2005, as amended, among the Borrower and LASALLE BANK NATIONAL ASSOCIATION, and payments of principal received on the Note
to which this Grid is attached:

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Schedule I

Organizational Identification Numbers

|CORPORATION                         |  | STATE        |  | STATE ID
|----------------------------------- |  | ------------ |  | --------
|Quixote Corporation                 |  | Delaware     |  | 0720523 
|Quixote Transportation Safety, Inc. |  | Delaware     |  | 2803660 
|Transafe Corporation                |  | Delaware     |  | 3197646 
|Energy Absorption Systems, Inc.     |  | Delaware     |  | 0904033 
|Energy Absorption (AL) LLC          |  | Delaware     |  | 3539333 
|Surface Systems, Inc.               |  | Missouri     |  | 00157025
|Nu-Metrics, Inc.                    |  | Pennsylvania |  | 978728  
|Highway Information Systems, Inc.   |  | Delaware     |  | 2867376 
|U.S. Traffic Corporation            |  | Delaware     |  | 3594608 
|Peek Traffic Corporation            |  | Delaware     |  | 3717402 

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AMENDED AND RESTATED REVOLVING LOAN NOTE

|$40,000,000 |  | Chicago, Illinois
November 7, 2007
|----------- |  | ----------------------------------

FOR VALUE RECEIVED, the undersigned, QUIXOTE CORPORATION, a Delaware corporation (the "Borrower"), promises to pay
to the order of LaSalle Bank National Association and its registered assigns (the "Lender"), on February 1, 2010, the principal sum of Forty
Million and No/100 Dollars ($40,000,000.00), or, if less, the aggregate unpaid principal amount of all loans made by the Lender to the Borrower from time to time pursuant to that certain Amended and
Restated Credit Agreement, dated as of April 20, 2005, between the Borrower and Lender as amended by the First Amendment to Amended and Restated Credit Agreement and Reaffirmation of
Guaranties, dated as of December 1, 2006, that certain Second Amendment to Amended and Restated Credit Agreement and Reaffirmation of Guaranties, dated as of March 15, 2007, and that
certain Third Amendment to Amended and Restated Credit Agreement and Reaffirmation of Guaranties as of the date hereof (together with all amendments, if any, from time to time made thereto, the
"Credit Agreement").

The
Borrower agrees to pay interest on the principal hereof remaining from time to time unpaid in accordance with Section 2.13 of the Credit Agreement.

All
payments of principal and interest on this Note shall be payable in lawful currency of the United States of America at the Agent's office at 135 South LaSalle Street, Chicago,
Illinois 60603, in immediately available funds.

This
Note evidences indebtedness incurred under, and is subject to the terms and provisions of, the Credit Agreement, to which reference is made for a statement of those terms and
provisions. Should the indebtedness represented by this Note or any part hereof be collected at law or in equity or in bankruptcy, receivership, or other court proceedings, or this Note be placed in
the hands of attorneys for collection after maturity (by declaration or otherwise), the undersigned agrees to pay, in addition to principal and interest due and payable hereon, reasonable attorneys'
and collection fees.

This
Note constitutes a renewal and restatement of, and replacement and substitution for, that certain Revolving Note, dated as of March 15, 2007 in the maximum principal amount
of Thirty Million and 00/100 Dollars ($30,000,000.00), executed by the Borrower and made payable to the order of the Bank (the "Prior Note"). The
indebtedness evidenced by the Prior Note is continuing indebtedness evidenced hereby, and nothing herein shall be deemed to constitute a payment, settlement or novation of the Prior Note, or to
release or otherwise adversely affect any lien, mortgage or security interest securing such indebtedness or any rights of the Bank against any guarantor, surety or other party primarily or secondarily
liable for such indebtedness.

[Signature
on following page]

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IN
WITNESS WHEREOF, the Borrower has executed this Note as of the date first above written

| |  | QUIXOTE CORPORATION
| |  | -------------------
| |  | By:                
| |  | Name:              
| |  | Title:             
| |  |                    

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