<PAGE>   1
                                 Exhibit 10.47

                                FIRST AMENDMENT

         THIS FIRST AMENDMENT (this "Amendment"), dated as of December __, 2000,
to the Credit Agreement referenced below, is by and among RailWorks Corporation,
a Delaware corporation (the "Borrower"), the Subsidiaries of the Borrower
identified on the signature pages hereto (the "Guarantors"), the Lenders
identified on the signature pages hereto and Bank of America, N.A., as
Administrative Agent. Terms used herein but not otherwise defined herein shall
have the meanings provided to such terms in the Credit Agreement.

                                  WITNESSETH

         WHEREAS, a $250 million credit facility has been extended to the
Borrower pursuant to the terms of that Amended and Restated Credit Agreement
dated as of April 28, 2000 (as amended, modified and supplemented from time to
time, the "Credit Agreement") among the Borrower, the Guarantors, the Lenders,
First Union National Bank, as Documentation Agent, and Bank of America, N.A., as
Administrative Agent;

         WHEREAS, the Borrower has requested certain modifications to the Credit
Agreement;

         WHEREAS, the requested modifications require the consent of the
Required Lenders; and

         WHEREAS, the Required Lenders have agreed to the requested
modifications on the terms and conditions set forth herein.

         NOW, THEREFORE, IN CONSIDERATION of the premises and other good and
valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, the parties hereto agree as follows:

         1.       Amendments. The Credit Agreement is amended in the following
         respects:

         1.1      The following definitions in Section 1.1 of the Credit
         Agreement are amended or added to read as follows:

                           "Acquired Company EBITDA" means, for any period for
                  the Person or Property which is the subject of an Acquisition,
                  the sum of net income for such period plus interest expense
                  for such period plus all provisions for any federal, state or
                  other domestic and foreign income taxes for such period plus
                  depreciation and amortization for such period, in each case on
                  a consolidated basis determined in accordance with GAAP
                  applied on a consistent basis. Except as otherwise expressly
                  provided, the applicable period shall be for the four
                  consecutive fiscal quarters immediately preceding the date of
                  determination or, if four consecutive fiscal quarters are not
                  available, then by annualization of the two consecutive fiscal
                  quarters immediately preceding as of the date of
                  determination.

                           "Available Revolving Committed Amount" shall have the
                  meaning provided in Section 2.1(a).

                           "Backlog/Contract Monitoring Report" shall have the
                  meaning provided in Section 7.2(f).

                           "Blocked Account" means a depository bank account of
                  the Borrower that is


                                       34
<PAGE>   2

                  governed by an assignment of collateral account or similar
                  agreement, in form acceptable to the Administrative Agent,
                  whereby the Borrower shall grant a security interest in such
                  account in favor of the Administrative Agent for the benefit
                  of the Lenders and shall acknowledge and agree that there
                  shall be no disbursements from such account except in payment
                  of the Borrower's obligations to the Lenders under this
                  Agreement.

                           "Borrowing Base" means, as of any day, an amount
                  equal to the sum of:

                           (a)      eighty-five percent (85%) of Eligible
                                    Receivables;

                           (b)      eighty-five percent (85%) of Eligible
                           Receivables Retainage;

                           (c)      sixty percent (60%) of Eligible Inventory;

                           (d)      the aggregate amount of cash and Cash
                           Equivalents held in a Blocked Account with the
                           Administrative Agent; and

                           (e)      the Borrowing Base Overadvance;

                  in each case as set forth in the most recent Borrowing Base
                  Certificate, with adjustments to give effect to Acquisitions
                  and Divestitures since the date of such Borrowing Base
                  Certificate on a Pro Forma Basis.

                           "Borrowing Base Certificate" means a statement of the
                  Borrowing Base and its components delivered pursuant to
                  Section 7.1(c), in form and content satisfactory to the
                  Administrative Agent and certified by the chief financial
                  officer, chief accounting officer, treasurer or assistant
                  treasurer of the Borrower to be true and correct as of the
                  date thereof.

                           "Borrowing Base Overadvance" means prior to and
                  including September 30, 2001, $15 million, and thereafter,
                  zero ($0).

                           "Consolidated EBITDA" means, for any period for the
                  Consolidated Group, the sum of Consolidated Net Income for
                  such period plus Consolidated Interest Expense for such period
                  plus all provisions for any federal, state or other domestic
                  and foreign income taxes for such period plus depreciation and
                  amortization for such period, in each case on a consolidated
                  basis determined in accordance with GAAP applied on a
                  consistent basis, but excluding for purposes hereof (i)
                  extraordinary gains and losses and related tax effects
                  thereon, and (ii) those special charges taken or to be taken
                  in the third fiscal quarter and fourth fiscal quarter of 2000
                  identified on Schedule 7.9 attached to the First Amendment.

                           "Consolidated Excess Cash Flow" means, for any fiscal
                  year of the Consolidated Group on a consolidated basis, an
                  amount equal to the sum of, without duplication, (a)
                  Consolidated EBITDA for such fiscal year minus (b) Contingent
                  Payments actually paid in cash during such fiscal year minus
                  (c) Consolidated Interest Expense actually paid during such
                  fiscal year minus (d) federal, state and other income taxes
                  actually paid by the Consolidated Group on a consolidated
                  basis during such fiscal year minus (e) Consolidated Capital
                  Expenditures made during such fiscal year minus (or plus) (f)
                  changes in working capital accounts [plus decreases (minus
                  increases) in accounts receivable, accounts receivable
                  retention, costs in excess of billings, inventory and items
                  set forth as "other current assets" on the consolidated and
                  consolidating balance sheet of the Consolidated Group and
                  minus decreases (plus increases) in accounts payable, billings
                  in excess of cost,


                                       35
<PAGE>   3

                  accrued payroll and items set forth as "other current
                  liabilities" on the consolidated and consolidating balance
                  sheet of the Consolidated Group] of the members of the
                  Consolidated Group, minus (g) the sum of all scheduled
                  payments of principal of Consolidated Funded Debt (including,
                  without limitation, the implied principal component of
                  payments due on Capital Leases and synthetic leases) during
                  such period minus (h) the sum of all scheduled reductions of
                  commitments of Consolidated Funded Debt (including, without
                  limitation, reductions in the Aggregate Revolving Committed
                  Amount required pursuant to Section 3.4(b)) during such period
                  minus (i) the amount of any voluntary prepayments of the
                  Tranche B Term Loan or (to the extent accompanied by a
                  reduction in the Aggregate Revolving Committed Amount) the
                  Revolving Loans plus (j) net proceeds from any recoveries of
                  any claims described on Schedule 3.3(c) attached to the First
                  Amendment.

                           "Consolidated Fixed Charges" means, for any period
                  for the Consolidated Group, the sum of (a) Consolidated
                  Interest Expense for such period (with adjustment to exclude
                  amortization of original issue discount on the Senior
                  Subordinated Notes) plus (b) Restricted Payments paid during
                  such period plus (c) the sum of all scheduled payments of
                  principal of Consolidated Funded Debt (including, without
                  limitation, the implied principal component of payments due on
                  Capital Leases and synthetic leases) for the period of four
                  consecutive fiscal quarters immediately following such period,
                  in each case on a consolidated basis determined in accordance
                  with GAAP applied on an consistent basis. Except as otherwise
                  expressly provided, the applicable period shall be for the
                  four consecutive fiscal quarters ending as of the date of
                  determination.

                           "Contingent Payments" means any payments payable (or
                  that may become payable) in settlement of any contingent
                  obligations incurred in connection with any Acquisition (other
                  than Support Obligations permitted by Section 8.1), including,
                  without limitation, any "earn-out payment" obligations.

                           "First Amendment" means the First Amendment to this
                  Credit Agreement dated as of December __, 2000.

                           "Overadvance Utilization Fee" shall have the meaning
                  assigned to such term in Section 3.5(d).

                           "Unadjusted Borrowing Base" means, as of any day, the
                  Borrowing Base less the Borrowing Base Overadvance.

         1.2      The pricing grid in the definition of "Applicable Percentage"
         is deleted in its entirety and replaced with the pricing grid below:


                                       36
<PAGE>   4

<TABLE>
<CAPTION>
                                              Applicable Percentages               Applicable Percentages
                                                for Revolving Loans               for Tranche B Term Loan
                                       -------------------------------------      ------------------------
                                        Eurodollar
                                          Loans
                       Consolidated        and         Base
         Pricing     Total Leverage    Letter of       Rate       Commitment      Eurodollar     Base Rate
          Level           Ratio        Credit Fee      Loans          Fee            Loans         Loans
         -------     ---------------   ----------      -----      ----------      ----------     ---------
         <S>         <C>               <C>             <C>        <C>             <C>            <C>
            I             > 5.5           4.00%        2.50%         0.750%          5.00%         3.50%
                          -
            II       > 5.0 but < 5.5      3.50%        2.00%         0.750%          4.50%         3.00%
                     -
           III       > 4.5 but < 5.0      3.25%        1.75%         0.625%          4.25%         2.75%
                     -
            IV       > 4.0 but < 4.5      3.00%        1.50%         0.625%          4.00%         2.50%
                     -
            V        > 3.5 but < 4.0      2.50%        1.00%         0.500%          3.50%         2.00%
                     -
            VI       > 3.0 but < 3.5      2.25%        0.75%         0.500%          3.50%         1.75%
                     -
           VII       > 2.5 but < 3.0      2.00%        0.50%         0.375%          3.50%         1.75%
                     -
           VIII      > 2.0 but < 2.5      1.75%        0.00%         0.300%          3.50%         1.75%
                     -
            IX       > 1.5 but < 2.0      1.50%        0.00%         0.300%          3.50%         1.75%
                     -
            X             < 1.5           1.25%        0.00%         0.250%          3.50%         1.75%
</TABLE>

         1.3      The definition of "Permitted Investments" in Section 1.1 is
         amended to include the following sentence at the end thereof:

                           It is acknowledged and agreed that the loans,
                  advances and investments permitted under the foregoing clause
                  (xii) shall not include additional loans, advances and
                  investments in or to Foreign Subsidiaries.

         1.4      Clause (i) of the proviso in Section 2.1(a) is amended to read
         as follows:

                           (i) with regard to the Revolving Lenders
                  collectively, the aggregate principal amount of Revolving
                  Obligations outstanding at any time shall not exceed ONE
                  HUNDRED TWENTY-FIVE MILLION DOLLARS ($125,000,000) (as such
                  amount may be reduced from time to time in accordance with the
                  provisions hereof, the "Aggregate Revolving Committed
                  Amount"), provided that of such amount only ONE HUNDRED
                  MILLION DOLLARS ($100,000,000) shall be available hereunder
                  (the "Available Revolving Committed Amount") until such time
                  as

                                    (A) for two consecutive fiscal quarters both
                           (i) the Consolidated Total Leverage Ratio shall be
                           less than 4.0:1.0 and (ii) the Consolidated Senior
                           Leverage Ratio shall be less than 2.5:1.0, in each
                           case as shown on the officer's certificate delivered
                           to the Administrative Agent pursuant to Section
                           7.2(a) as of the end of such quarters, or

                                    (B) all (100%) of the Revolving Lenders and
                           Tranche B Term Lenders holding at least sixty-six and
                           two thirds percent (66-2/3%) of the outstanding
                           principal amount of the Tranche B Term Loan shall
                           otherwise agree;

         1.5      Section 2.2(e) of the Credit Agreement is hereby deleted in
         its entirety.

         1.6      Section 2.2(f) of the Credit Agreement is hereby deleted in
         its entirety.

         1.7      Clause (c) of Section 2.4 of the Credit Agreement is amended
         to read as follows:


                                       37
<PAGE>   5

                           (c)      Tranche B Term Loan. The principal amount of
                  the Tranche B Term Loan shall be due and payable in twenty-six
                  (26) consecutive quarterly installments, as follows:

<TABLE>
<CAPTION>
                                            Principal                                 Principal
                                          Amortization                               Amortization
                         Date                Payment               Date                 Payment
                  ------------------      ------------      ------------------       ------------
                  <S>                     <C>               <C>                      <C>
                  June 30, 2000              $250,000       September 30, 2003         $1,875,000
                  September 30, 2000         $250,000       December 31, 2003          $1,875,000
                  December 31, 2000          $250,000       March 31, 2004             $2,500,000
                  March 31, 2001             $250,000       June 30, 2004              $2,500,000
                  June 30, 2001              $250,000       September 30, 2004         $2,500,000
                  September 30, 2001         $250,000       December 31, 2004          $9,781,250
                  December 31, 2001          $250,000       March 31, 2005             $9,781,250
                  March 31, 2002           $1,250,000       June 30, 2005              $9,781,250
                  June 30, 2002            $1,250,000       September 30, 2005         $9,781,250
                  September 30, 2002       $1,250,000       December 31, 2005          $9,781,250
                  December 31, 2002        $1,250,000       March 31, 2006             $9,781,250
                  March 31, 2003           $1,875,000       June 30, 2006              $9,781,250
                  June 30, 2003            $1,875,000       September 30, 2006         $9,781,250
                                                                                     ------------

                                                            Total                    $100,000,000
</TABLE>

         1.8      Section 3.3(b)(ii) (Mandatory Prepayments in respect of
         Divestitures) is amended to read as follows:

                           The Loans shall be prepaid as hereafter provided in
                  an amount equal to one hundred percent (100%) of the Net Cash
                  Proceeds received from Divestitures (other than in the
                  ordinary course of business) to the extent that the aggregate
                  amount of Net Cash Proceeds therefrom shall exceed $1 million
                  in any fiscal year.

         1.9      A new subclause (v) is added to clause (b) of Section 3.3 of
         the Credit Agreement to read as follows:

                           (v)      Consolidated Excess Cash Flow. Until such
                  time as the Consolidated Total Leverage Ratio shall be less
                  than 3.0:1.0 as of the end of two consecutive fiscal quarters
                  as shown on the officer's certificate delivered to the
                  Administrative Agent pursuant to Section 7.2(a), the Borrower
                  will, within ninety (90) days after the end of each fiscal
                  year (commencing with the fiscal year ending December 31,
                  2001), prepay the Loans as hereafter provided in an amount
                  equal to seventy-five percent (75%) of the Consolidated Excess
                  Cash Flow for the prior fiscal year.

         1.10     A new subclause (C) is added to clause (c)(ii) of Section 3.3
         of the Credit Agreement to read as follows:

                           (C)      Prepayments of Consolidated Excess Cash
                  Flow. Mandatory prepayments made under this Section 3.3 in
                  respect of Consolidated Excess Cash Flow shall be applied
                  fifty percent (50%) to the Tranche B Term Loan (to the
                  principal amortization installments thereof in inverse order
                  of maturity) and fifty percent (50%) to the Revolving
                  Obligations (with a corresponding permanent reduction in the
                  Revolving Committed Amount in an amount equal to all amounts
                  applied to the Revolving Obligations pursuant to this Section
                  3.3(c)(ii)(C)). Such mandatory prepayments shall be applied
                  first to Base Rate Loans, then to Eurodollar Loans in direct
                  order of Interest Period maturities, then to


                                       38
<PAGE>   6

                  Quoted Rate Swingline Loans in direct order of Interest Period
                  maturities and then to a cash collateral account to secure LOC
                  Obligations.

         1.11     Clause (b) of Section 3.4 of the Credit Agreement is
         renumbered as clause (c) thereof and a new clause (b) is added thereto
         to read as follows:

                           (b)      Mandatory Reductions. The Aggregate
                  Revolving Committed Amount and the Available Revolving
                  Committed Amount each shall be automatically and permanently
                  reduced on the date set forth below by the amount set forth
                  opposite such date:

<TABLE>
<CAPTION>
                           Date                                 Amount
                           ----                                 ------
                           <S>                                <C>
                           June 30, 2002                      $2,500,000
                           December 31, 2002                  $2,500,000
                           June 30, 2003                      $3,750,000
                           December 31, 2003                  $3,750,000
                           June 30, 2004                      $7,500,000
</TABLE>

         1.12     The first sentence of Section 3.5(a)(i) of the Credit
         Agreement is amended to read as follows:

                           In consideration of the Revolving Commitments, the
                  Borrower agrees to pay to the Administrative Agent for the
                  ratable benefit of the Lenders a commitment fee (the
                  "Commitment Fee") equal to the sum of (i) the Applicable
                  Percentage per annum on the average daily unused amount of the
                  Available Revolving Committed Amount for the applicable period
                  plus (ii) one-half of the Applicable Percentage per annum on
                  the average daily amount by which the Aggregate Revolving
                  Committed Amount exceeds the Available Revolving Committed
                  Amount for the applicable period.

         1.13     A new clause (d) is added to Section 3.5 of the Credit
         Agreement to read as follows:

                           (d)      Borrowing Base Overadvance Fee. In
                  consideration of the Borrowing Base Overadvance, the Borrower
                  agrees to pay to the Administrative Agent, for the ratable
                  benefit of the Lenders, an overadvance utilization fee (the
                  "Overadvance Utilization Fee") equal to one and one-fourth
                  percent (1.25%) per annum on the amount by which the aggregate
                  principal amount of outstanding Obligations exceeds the
                  Unadjusted Borrowing Base on any day during the applicable
                  period. The Overadvance Utilization Fee shall be payable
                  quarterly in arrears on the last Business Day of each March,
                  June, September and December and on the Termination Date,
                  beginning with the payment due December 31, 2000, for the
                  quarter (or a portion thereof) then ending.

         1.14     Section 6.15 (Purpose of Extensions of Credit) is amended to
         read as follows:

                           The Extensions of Credit shall be used (i) to
                  refinance existing Funded Debt and (ii) to finance working
                  capital, capital expenditures and other lawful corporate
                  purposes, including Permitted Acquisitions; provided that
                  notwithstanding the foregoing, proceeds of Extensions of
                  Credit may not be used to make earn-out payments owing under
                  seller financing obligations unless after giving effect to all
                  such payments there would be at least $15 million of
                  availability remaining hereunder.


                                       39
<PAGE>   7

         1.15     Subclause (ii) of clause (b) of Section 7.1 is renumbered as
         clause (iii) and a new clause (ii) is added thereto to read as follows:

                           (ii)     within sixty (60) days after the end of the
                  month of December and thirty (30) days after the end of each
                  other calendar month, a company-prepared consolidated and
                  consolidating balance sheet of the Consolidated Group as of
                  the end of such calendar month and related company-prepared
                  consolidated and consolidating statements of operations,
                  shareholders' equity and cash flows for such calendar month
                  and for the fiscal year to date, in form and substance
                  satisfactory to the Administrative Agent and the Required
                  Lenders, together with the monthly information package
                  prepared for the Board of Directors and the weekly cash flow
                  projections and reconciliation provided under Section 7.2(h);

         1.16     Clause (c) of Section 7.1 of the Credit Agreement is amended
         to read as follows:

                           (c)(i) by no later than the 15th day of each calendar
                  month, a Borrowing Base Certificate as of the last day of the
                  immediately preceding calendar month, and (ii) by no later
                  than the last day of each calendar month, an updated Borrowing
                  Base Certificate reflecting the Borrowing Base as of the last
                  day of the immediately preceding calendar month, indicating in
                  each case the outstanding Obligations owing as of the date of
                  determination;

         1.17     Clause (f) of Section 7.2 of the Credit Agreement is
         renumbered as clause (i) thereof and new clauses (f), (g) and (h) are
         added thereto to read as follows:

                           (f)      Contract Monitoring Report. Concurrently
                  with the delivery of the financial statements referred to in
                  Sections 7.1(a) and 7.1(b) above, a contract monitoring report
                  for all contracts with estimated revenues of $10 million or
                  more (the "Backlog/Contract Monitoring Report"), in the form
                  attached as Schedule 7.1(f) to the First Amendment;

                           (g)      Quarterly Reconciliation Report.
                  Concurrently with the delivery of the financial statements
                  referred to in Sections 7.1(a) and 7.1(b) above commencing
                  with financial statements for the fiscal quarter ending March
                  31, 2001, a report in a form acceptable to the Administrative
                  Agent reflecting a comparison between the actual consolidated
                  and consolidating income statements, balance sheets and cash
                  flow forecasts for such quarter and the projections contained
                  in the Business Plan prepared in connection with (and as
                  defined in) the First Amendment;

                           (h)      Cash Flow Reports. As soon as available, and
                  in any event within five (5) Business Days following the first
                  day of each two week period (commencing with the two week
                  period beginning December 4, 2000), a report, in a form
                  acceptable to the Administrative Agent, that includes (i) a
                  detailed cash flow projection of the Borrower for the then
                  upcoming six weeks, on a consolidated and consolidating basis,
                  and (ii) a variance analysis reflecting a detailed comparison
                  between the actual cash flow computations of the Borrower
                  through the end of the previous two week period on a
                  consolidated and consolidating basis and those projected for
                  such two week period in the most recent cash flow projection
                  previously provided to the Administrative Agent in accordance
                  with this Section; provided, however, that the first of such
                  reports shall be delivered on or before December __, 2000 and
                  shall not include a variance analysis.

         1.18     Clause (a) of Section 7.9 of the Credit Agreement is amended
         to read as follows:


                                       40
<PAGE>   8

                           (a)      Consolidated Total Leverage Ratio. As of the
                  end of each fiscal quarter of the members of the Consolidated
                  Group, the Consolidated Total Leverage Ratio shall not be
                  greater than the ratio set forth below:

<TABLE>
<CAPTION>
                                    Fiscal Quarter End                           Ratio
                                    ------------------                           -----
                                    <S>                                         <C>
                                    December 31, 2000                           5.75:1.0
                                    March 31, 2001                              5.75:1.0
                                    June 30, 2001                               5.75:1.0
                                    September 30, 2001                          5.10:1.0
                                    December 31, 2001                           4.50:1.0
                                    March 31, 2002                              4.25:1.0
                                    June 30, 2002                               4.25:1.0
                                    September 30, 2002                          4.25:1.0
                                    December 31, 2002 and thereafter            4.00:1.0
</TABLE>

         1.19     Clause (b) of Section 7.9 of the Credit Agreement is amended
         to read as follows:

                           (b)      Consolidated Senior Leverage Ratio. As of
                  the end of each fiscal quarter of the members of the
                  Consolidated Group, the Consolidated Senior Leverage Ratio
                  shall not be greater than the ratio set forth below:

<TABLE>
<CAPTION>
                                    Fiscal Quarter End                           Ratio
                                    ------------------                           -----
                                    <S>                                         <C>
                                    December 31, 2000                           3.00:1.0
                                    March 31, 2001                              3.00:1.0
                                    June 30, 2001                               3.00:1.0
                                    September 30, 2001                          2.75:1.0
                                    December 31, 2001 and thereafter            2.50:1.0
</TABLE>

         1.20     Clause (c) of Section 7.9 of the Credit Agreement is amended
         to read as follows:

                           (c)      As of the end of each fiscal quarter of the
                  members of the Consolidated Group, Consolidated Net Worth
                  shall be not less than the sum of (i) the greater of (A) an
                  amount equal to ninety percent (90%) of Consolidated Net Worth
                  as of December 31, 2000 or (B) $90 million plus (ii) on the
                  last day of each fiscal quarter to end after September 30,
                  2000, seventy-five percent (75%) of Consolidated Net Income
                  for the fiscal quarter (but not less than zero), such
                  increases to be cumulative, plus (iii) one hundred percent
                  (100%) of any increases in Consolidated Net Worth resulting
                  from Equity Transactions occurring after the date of the First
                  Amendment.

         1.21     Clause (d) of Section 7.9 of the Credit Agreement is amended
         to read as follows:

                           (d)      Consolidated Fixed Charge Coverage Ratio. As
                  of the end of each fiscal quarter of the members of the
                  Consolidated Group, the Consolidated Fixed Charge Coverage
                  Ratio shall not be less than the ratio set forth below:


                                       41
<PAGE>   9

<TABLE>
<CAPTION>
                                    Fiscal Quarter End                           Ratio
                                    ------------------                           -----
                                    <S>                                         <C>
                                    December 31, 2000                           1.20:1.0
                                    March 31, 2001                              1:10:1.0
                                    June 30, 2001                               1:00:1.0
                                    September 30, 2001                          1.20:1.0
                                    December 31, 2001                           1.35:1.0
                                    March 31, 2002                              1.35:1.0
                                    June 30, 2002                               1.40:1.0
                                    September 30, 2002                          1.40:1.0
                                    December 31, 2002                           1.40:1.0
                                    March 31, 2003                              1.50:1.0
                                    June 30, 2003                               1.50:1.0
                                    September 30, 2003                          1.50:1.0
                                    December 31, 2003                           1.50:1.0
                                    March 31, 2004                              1.35:1.0
                                    June 30, 2004 and thereafter                1.20:1.0
</TABLE>

         1.22     A new clause (f) is added to Section 7.9 of the Credit
         Agreement to read as follows:

                           (f) Consolidated EBITDA. As of the end of each fiscal
                  quarter of the members of the Consolidated Group, Consolidated
                  EBITDA for the fiscal quarter then ended shall not be less
                  than the amount set forth below:

<TABLE>
<CAPTION>
                                                                             Minimum Quarterly
                                    Fiscal Quarter End                      Consolidated EBITDA
                                    ------------------                      -------------------
                                    <S>                                     <C>
                                    December 31, 2000                           $10,000,000
                                    March 31, 2001                              $10,000,000
                                    June 30, 2001                               $17,500,000
                                    September 30, 2001                          $20,000,000
                                    December 31, 2001                           $17,500,000
</TABLE>

         1.23     A new Section 7.15 is added to read as follows:

                           7.15     Deposit Accounts. No later than January 31,
                  2001, cause each of the members of the Consolidated Group
                  (other than Foreign Subsidiaries) to maintain any and all
                  deposit accounts either with the Administrative Agent or with
                  Lenders that have, with the Administrative Agent and the
                  applicable Credit Party, executed tri-party agency agreements
                  in substantially the form attached as Exhibit 7.15 or
                  otherwise in form reasonably acceptable to the Borrower and
                  the Administrative Agent; provided, however, that any of such
                  members of the Consolidated Group may maintain deposit
                  accounts with banking institutions other than the
                  Administrative Agent or the Lenders so long as the aggregate
                  amount of funds contained in all such deposit accounts does
                  not exceed $2,000,000. In the case of Foreign Subsidiaries, if
                  on May 31 of any year the aggregate amount of cash and Cash
                  Equivalents held by Foreign Subsidiaries on such date exceeds
                  the Funded Debt of the Foreign Subsidiaries (other than
                  intracompany loans) on such date, the Borrower shall cause the
                  Foreign Subsidiaries to promptly transfer to the Borrower or
                  its Domestic Subsidiaries in the United States.

         1.24     Section 8.4 of the Credit Agreement is amended to read as
         follows:

                  8.4      Acquisitions.  Make any Acquisition, unless

                                    (a)      the Consolidated Total Leverage
                           Ratio shall have been less than 3.0:1.0 as of the end
                           of two consecutive fiscal quarters occurring after
                           the date of the First Amendment as shown on the
                           officer's


                                       42
<PAGE>   10

                           certificate delivered to the Administrative Agent
                           pursuant to Section 7.2(a);

                                    (b)      the total consideration (cash and
                           non-cash consideration, including, without
                           limitation, Indebtedness assumed, capital stock of
                           the Borrower issued in connection with the
                           Acquisition and the maximum aggregate amount of
                           Contingent Payments payable in connection with the
                           Acquisition) for any single Acquisition (or series of
                           related Acquisitions) shall not exceed $15,000,000 in
                           any instance;

                                    (c)      the total consideration (cash and
                           non-cash consideration, including, without
                           limitation, Indebtedness assumed, capital stock of
                           the Borrower issued in connection with the
                           Acquisition and the maximum aggregate amount of
                           Contingent Payments payable in connection with the
                           Acquisition) for all Acquisitions shall not exceed
                           $30,000,000 in any fiscal year;

                                    (d)      the Person or Property that is the
                           subject of the Acquisition shall have generated
                           positive Acquired Company EBITDA;

                                    (e)      in the case of an Acquisition of
                           Property (other than capital stock or other equity
                           interest of any Person), such Property which is the
                           subject of the Acquisition shall be located in the
                           United States of America;

                                    (f)      in the case of an Acquisition of
                           the capital stock or other equity interest of any
                           Person, such Person shall be organized under the laws
                           of, and located in, any of the States of the United
                           States of America or the District of Columbia and all
                           of the Property of such Person shall be located in
                           the United States of America;

                                    (g)      the Property acquired (or the
                           Property of the Person acquired) in the Acquisition
                           is used or useful in the same or a similar line of
                           business as the Borrower and its Subsidiaries were
                           engaged in on the date of the First Amendment;

                                    (h)      the board of directors of the
                           Person which is, or whose Property is, the subject of
                           the Acquisition shall have approved the Acquisition
                           without material condition or contingency;

                                    (i)      no Default or Event of Default
                           would exist after giving effect to the Acquisition,
                           determined in the case of financial covenant
                           compliance on a Pro Forma Basis for the period of
                           four consecutive fiscal quarters immediately
                           preceding the date of the Acquisition and as
                           otherwise set forth in Section 1.3(b).

                  Any consent of the Required Lenders requested by the Borrower
                  under this Section 8.4 shall not be arbitrarily withheld or
                  unreasonably delayed.

         1.25     A new Section 8.14 is added to read as follows:

                           8.14     Limitation of Payment of Intracompany Loans.
                  Make any principal payments on any Indebtedness owing to
                  Foreign Subsidiaries, except for


                                       43
<PAGE>   11

                  principal payments of up to $4,000,000 in the aggregate on
                  Indebtedness owing to Foreign Subsidiaries on the date of the
                  First Amendment so long as no Default or Event of Default
                  exists immediately prior thereto or would exist immediately
                  after giving effect thereto.

         1.26 The Attachment for Computation of Financial Covenants attached to
         the Form of Officer's Certificate in Schedule 7.2(b) is amended to read
         as attached hereto.

         2.       Waiver.

                  (a)      The Lenders hereby waive any Default or Event of
         Default that exists solely as a result of the Borrower's failure to
         comply with Section 7.9(a) (Consolidated Total Leverage Ratio), Section
         7.9(b) (Consolidated Senior Leverage Ratio), Section 7.9(c)
         (Consolidated Net Worth) and Section 7.9(d) (Consolidated Fixed Charge
         Coverage Ratio) for any period ended on or before September 30, 2000.
         The foregoing waiver shall not modify or affect the Borrower's
         obligation to comply with Section 7.9(a), Section 7.9(b), Section
         7.9(c) and Section 7.9(d) at all times after September 30, 2000.

                  (b)      The Lenders hereby waive any Default or Event of
         Default that exists solely as a result of the Borrower's failure to
         comply with Section 5.2(b) of the Security Agreement in connection with
         (i) the change in corporate name of (A) Annex Railroad Builders Inc.
         (now known as RailWorks Track Services, Inc.), (B) RWKS Transit, Inc.
         (now known as RailWorks Transit, Inc.), (C) Railroad Service, Inc. (now
         known as RailWorks Track Systems, Inc.), (D) RailWorks Rail Services,
         Inc. (now known as RailWorks Rail Products & Services, Inc.) and (E)
         Twigg Corporation (now known as RWKS Construction, Inc.), and (ii) the
         change in corporate structure of Impulse Electric Enterprises of New
         York, Inc. and Sheldon Electric, Inc., both of which merged into L.K.
         Comstock & Company, Inc. The foregoing waiver shall not modify or
         affect the Borrower's obligation to comply with Section 5.2(b) of the
         Security Agreement in all other cases.

         3.       Covenants. The Borrower hereby agrees to provide the
following:

                  (a)      Report Concerning Strategic Divestitures. On or
         before March 31, 2001, the Borrower will provide a report to the
         Administrative Agent on the advisability and feasibility of a sale or
         other divestiture of non-strategic businesses.

                  (b)      Delivery of Detailed 2001 Business Plan. On or before
         December 31, 2000, a detailed "bottoms-up" cash flow budget for fiscal
         year 2001 for the Borrower, including consolidated and consolidating
         income statements, balance sheets and cash flow forecasts by month,
         which shall be based upon and supported by income statements, balance
         sheets and cash flow forecasts from each operating group within the
         Borrower (including the Transit Group).

                  (c)      Delivery of Backlog/Contract Monitoring Report. On or
         before December 31, 2000, a detailed Backlog/Contract Monitoring Report
         for the fiscal quarter ended September 30, 2000, as provided in Section
         7.2(f), as amended.

         4.       Conditions Precedent. This Amendment shall be effective upon
satisfaction of the following conditions precedent:

                  (a)      receipt by the Administrative Agent of multiple
         counterparts of this Amendment executed by the Credit Parties and the
         Required Lenders;


                                       44
<PAGE>   12

                  (b)      receipt by the Administrative Agent of an opinion of
         counsel to the Credit Parties relating to this Amendment, which opinion
         shall be in form and substance satisfactory to the Required Lenders;

                  (c)      receipt by the Administrative Agent and the Lenders
         of a detailed "bottoms-up" cash flow budget for fiscal year 2001 for
         the Transit Group of the Borrower, including consolidated and
         consolidating income statements, balance sheets and cash flow forecasts
         by month;

                  (d)      receipt by the Administrative Agent of a Blocked
         Account agreement executed by the Borrower, which agreement shall be in
         form and substance satisfactory to the Administrative Agent;

                  (e)      receipt by the Administrative Agent, for the ratable
         benefit of the Lenders which consent to this Amendment on the date
         hereof (the "Consenting Lenders"), of an amendment fee equal to 10
         basis points (0.10%) on the aggregate Commitments (after giving effect
         to this Amendment) of the Consenting Lenders; and

                  (f)      receipt by the Administrative Agent of all other fees
         and expenses due in connection with this Amendment;

         5.       Representations.

                  (a)      The Borrower hereby affirms that the representations
         and warranties set forth in the Credit Agreement and the other Credit
         Documents are true and correct as of the date hereof (except those
         which expressly relate to an earlier period).

                  (b)      Each of the Credit Parties hereby affirms that it has
         the corporate or other power and authority, and the legal right, to
         make, deliver and perform this Amendment and has taken all necessary
         action to authorize the execution, delivery and performance of this
         Amendment, and that this Amendment constitutes a legal, valid and
         binding obligation enforceable in accordance with its terms, except as
         enforceability may be limited by applicable bankruptcy, insolvency,
         reorganization, moratorium or similar laws affecting the enforcement of
         creditors' rights generally and by general equitable principles
         (whether enforcement is sought by proceedings in equity or at law).

         6.       Release. Each Credit Party hereby represents and warrants that
it has no claims, counterclaims, offsets, or defenses to the Credit Documents or
to the performance of its obligations thereunder. In consideration of the
Lenders' willingness to enter into this Amendment, each Credit Party hereby
releases the Administrative Agent, the Lenders, and the Administrative Agent's
and the Lenders' respective officers, employees, representatives, agents,
counsel, trustees and directors from any and all actions, causes of action,
claims, demands, damages and liabilities or whatever kind or nature, in law or
in equity, now known or unknown, suspected or unsuspected, that may exist in
connection with any of the Credit Documents or the Obligations, to the extent
that any of the foregoing arises from any action or failure to act on or prior
to the date hereof.

         7.       Reaffirmation of Guaranty. Each Guarantor (i) acknowledges and
consents to all of the terms and conditions of this Amendment, (ii) affirms all
of its obligations under the Credit Documents and (iii) agrees that this
Amendment and all documents executed in connection herewith do not operate to
reduce or discharge such Guarantor's obligations under the Credit Agreement or
the other Credit Documents.


                                       45
<PAGE>   13

         8.       No Other Changes. Except as modified hereby, all of the terms
and provisions of the Credit Agreement and the other Credit Documents (including
schedules and exhibits thereto) shall remain in full force and effect.

         9.       Costs and Expenses. The Borrower agrees to pay all reasonable
costs and expenses of the Administrative Agent in connection with the
preparation, execution and delivery of this Amendment, including, without
limitation, the reasonable fees and expenses of Moore & Van Allen, PLLC.

         10.      Counterparts. This Amendment may be executed in any number of
counterparts, each of which when so executed and delivered shall be deemed an
original and it shall not be necessary in making proof of this Amendment to
produce or account for more than one such counterpart.

         11.      Governing Law. This Amendment shall be deemed to be a contract
made under, and for all purposes shall be construed in accordance with, the laws
of the State of New York.

                  [Remainder of Page Intentionally Left Blank]


                                       46
<PAGE>   14

         IN WITNESS WHEREOF, each of the parties hereto has caused a counterpart
of this Amendment to be duly executed and delivered as of the date first above
written.

BORROWER:     RAILWORKS CORPORATION,
              a Delaware corporation

              By:
                 -----------------------------------------
              Name:  Michael R. Azarela
              Title: President

GUARANTORS:   ALPHA-KEYSTONE ENGINEERING, INC., a Pennsylvania corporation
              BIRMINGHAM WOOD, INC., an Alabama corporation
              BREAKING TECHNOLOGY CORP., a New York corporation
              BREAKING TECHNOLOGY & EQUIPMENT, INC., a New York corporation
              COMSTOCK HOLDINGS, INC., a Delaware corporation
              COMTRAK CONSTRUCTION, INC., a Georgia corporation
              CONDON BROTHERS, INC., a Washington corporation
              CPI CONCRETE PRODUCTS, INCORPORATED, a Tennessee corporation
              EARL CAMPBELL CONSTRUCTION COMPANY, INC., a Texas corporation
              FCM RAIL, LTD., a Michigan corporation
              GANTREX CORPORATION, a Pennsylvania corporation
              H.P. MCGINLEY, INC., a Pennsylvania corporation
              HSQ TECHNOLOGY, a California corporation
              KENNEDY RAILROAD BUILDERS, INC., a Pennsylvania corporation
              L.K. COMSTOCK & COMPANY, INC., a New York corporation
              M-TRACK ENTERPRISES, INC., a New York corporation
              MCCORD TREATED WOOD, INC., an Alabama corporation
              MERIT RAILROAD CONTRACTORS, INC., a Missouri corporation
              MIDWEST CONSTRUCTION SERVICES, INC., an Indiana corporation
              MIDWEST RAILROAD CONSTRUCTION AND MAINTENANCE CORPORATION
                       OF WYOMING, a Wyoming corporation
              MINNESOTA RAILROAD SERVICE, INC., a Tennessee corporation
              NEOSHO ASIA, INC., a Kansas corporation
              NEOSHO CENTRAL AMERICA, INC., a Kansas corporation
              NEOSHO CONSTRUCTION COMPANY, INCORPORATED, a Kansas corporation
              NEOSHO CONTRACTORS, INC., a Wyoming corporation
              NEOSHO INCORPORATED, INC., a Kansas corporation
              NEOSHO INTERNATIONAL, INC., a Kansas corporation
              NEW ENGLAND RAILROAD CONSTRUCTION CO., a Connecticut corporation
              NORTHERN RAIL SERVICE AND SUPPLY COMPANY, INC.,
                       a Michigan corporation

              By:
                 -----------------------------------------------------
              Name:  Michael R. Azarela
              Title: Executive Vice President of each of the foregoing

                           [SIGNATURE PAGES CONTINUE]


                                       47
<PAGE>   15

              RAILCORP, INC., an Ohio corporation
              RAILWORKS RAIL PRODUCTS & SERVICES, INC., a Kansas corporation
              RAILWORKS TRACK SERVICES, INC., an Indiana corporation
              RAILWORKS TRACK SYSTEMS, INC., a Nevada corporation
              RAILWORKS TRANSIT, INC., a New York corporation
              RAILWORKS WOOD PRODUCTS, INC., a Delaware corporation
              RWKS CONSTRUCTION, INC., a Maryland corporation
              SOUTHERN INDIANA WOOD PRESERVING CO., INC., an Indiana corporation
              U.S. RAILWAY SUPPLY, INC., an Indiana corporation
              U.S. TRACKWORKS, INC., a Michigan corporation
              V&R ELECTRICAL CONTRACTORS, INC., a New York corporation
              WM. A. SMITH CONSTRUCTION CO., INC., a Texas corporation
              WOOD WASTE ENERGY, INC., a Virginia corporation
              W.T. BYLER CO., INC., a Texas corporation



              By:
                 -----------------------------------------------------
              Name:  Michael R. Azarela
              Title: Executive Vice President of each of the foregoing

              RAILWORKS TRANSIT SYSTEMS, INC., a Delaware corporation
              RAILWORKS CANADA, INC., a Delaware corporation



              By:
                 -----------------------------------------------------
              Name:  John P. Nuzzo
              Title: Assistant Secretary of each of the foregoing



              By:
                 -----------------------------------------------------
              Name:  Michael R. Azarela
              Title: Executive Vice President of each of the foregoing

              DURA-WOOD LLC, a Delaware limited liability company


              By:      MCCORD TREATED WOOD, INC.,
                       an Alabama corporation, its managing member



                       By:
                          --------------------------------------------
                       Name:  Michael R. Azarela
                       Title: Executive Vice President

                           [SIGNATURE PAGES CONTINUE]


                                       48
<PAGE>   16

LENDERS:      BANK OF AMERICA, N.A.,
              individually in its capacity as a
              Lender and in its capacity as Administrative Agent



              By:
                 --------------------------
              Name:
              Title:

              FIRST UNION NATIONAL BANK



              By:
                 --------------------------
              Name:
              Title:

              SUMMIT BANK



              By:
                 --------------------------
              Name:
              Title:

              M&T BANK



              By:
                 --------------------------
              Name:
              Title:

              KEY BANK NATIONAL ASSOCIATION



              By:
                 --------------------------
              Name:
              Title:

              BANK ONE, MICHIGAN



              By:
                 --------------------------
              Name:
              Title:

              COMERICA BANK



              By:
                 --------------------------
              Name:
              Title:

                           [SIGNATURE PAGES CONTINUE]


                                       49
<PAGE>   17

              STATE STREET BANK AND TRUST COMPANY,
              as Trustee for GENERAL MOTORS WELFARE BENEFITS TRUST



              By:
                 -------------------------------------------------
              Name:
              Title:

              STATE STREET BANK AND TRUST COMPANY, as Trustee for
              GENERAL MOTORS EMPLOYEES GLOBAL GROUP PENSION TRUST



              By:
                 -------------------------------------------------
              Name:
              Title:

              ALLFIRST BANK



              By:
                 -------------------------------------------------
              Name:
              Title:

              HELLER FINANCIAL, INC.



              By:
                 -------------------------------------------------
              Name:
              Title:

              THE PROVIDENT BANK



              By:
                 -------------------------------------------------
              Name:
              Title:

              FOOTHILL INCOME TRUST II, L.P.



              By:
                 -------------------------------------------------
              Name:
              Title:

              METROPOLITAN PROPERTY AND CASUALTY INSURANCE COMPANY



              By:
                 -------------------------------------------------
              Name:
              Title:

                           [SIGNATURE PAGES CONTINUE]


                                       50
<PAGE>   18

              FLOATING RATE PORTFOLIO
              By:  INVESCO Senior Secured Management, Inc.,
                   as attorney in fact



              By:
                 ----------------------------------------------
              Name:
              Title:

              AVALON CAPITAL LTD.
              By:  INVESCO Senior Secured Management, Inc.



              By:
                 ----------------------------------------------
              Name:
              Title:

              CERES II FINANCE LTD
              By:  INVESCO Senior Secured Management, Inc.,
                   as Sub-Management Agent (Financial)



              By:
                 ----------------------------------------------
              Name:
              Title:

              VAN KAMPEN PRIME RATE INCOME TRUST



              By:
                 ----------------------------------------------
              Name:
              Title:

              VAN KAMPEN CLO I, LIMITED



              By:
                 ----------------------------------------------
              Name:
              Title:

              VAN KAMPEN SENIOR INCOME TRUST



              By:
                 ----------------------------------------------
              Name:
              Title:

              J.H. WHITNEY MARKET VALUE FUND, L.P.



              By:
                 ----------------------------------------------
              Name:
              Title:


                                       51
<PAGE>   19

                                 Schedule 3.3(c)

                          Schedule of Claims Recoveries


                                       52
<PAGE>   20

                                 Schedule 7.1(f)

                   Form of Contract/Backlog Monitoring Report


                                       53

<PAGE>   21

                                 Exhibit 7.2(b)

                   Form of Attachment to Officer's Certificate
                     For Computation of Financial Covenants



                                       54
<PAGE>   22

                                  Schedule 7.9

           Special Charges taken in Third and Fourth Quarters of 2000


                                       55
<PAGE>   23

                                  Schedule 7.15

Form of Tri-Party Agency Agreement


                                       56