Nicor Inc.
                                                                Form S-8
                                                                Exhibit 4.03
                                 FIRST AMENDMENT
                                       OF
                      BIRDSALL INC. RETIREMENT SAVINGS PLAN
                (As Amended and Restated as of January 1, 2001)

      WHEREAS, Birdsall Inc. (the "Company") maintains the
Birdsall Inc. Retirement Savings Plan (the "Plan");

      WHEREAS, it is now desirable to amend the Plan to comply with changes
required and permitted by the Economic Growth and Tax Relief Reconciliation Act
of 2001 ("EGTRRA") and to make certain other clarifying changes to the Plan; and

      WHEREAS, the amendment to the Plan which is made hereby is intended as
good faith compliance with the requirements of EGTRRA and is to be construed in
accordance with EGTRRA and guidance issued thereunder;

      NOW, THEREFORE, by virtue and in exercise of the authority granted to the
Company by the terms of the Plan, the Plan is hereby amended in the following
particulars, all effective as of January 1, 2002 unless otherwise specified:

1. By substituting the following for subsection 4.7 of the Plan:

      "4.7 Rollover Contributions. Subject to the following provisions of this
subsection 4.7, an employee who satisfies the requirements of subsection 2.1
(other than the age and service requirements) and any participant who is
actively employed by an employer or an affiliate may, with the consent of the
committee, make a rollover contribution (as defined below) to the trustees. The
term `rollover contribution' means:

      (a)  a cash contribution to the plan by the participant of amounts
           distributed from an eligible plan (as defined below) or distributed
           from an individual retirement account and constituting a `rollover
           contribution' as described in section 408(d)(3) of the code and made
           within 60 days of receipt of such amount; or

      (b)  a cash payment to the plan by another qualified plan described in
           section 401(a) of the code as a direct rollover (as contemplated by
           section 401(a)(31) of the code) on behalf of and at the direction of
           the participant,

provided such distributed or directly rolled over amounts are permitted to be
rolled over to a qualified plan under the applicable provisions of the code as
then in effect and such amounts do not consist of after-tax employee
contributions or other amounts which would not otherwise be includible in gross
income. For purposes of this subsection 4.7, an `eligible plan' shall mean a
qualified plan described in section 401(a) or 403(a) of the code, an annuity
contract described in section 403(b) of the code, an eligible plan under section
457(b) of the code which is maintained by a state, political subdivision of a
state, or any agency or instrumentality of a state or political subdivision of a
state, or an individual retirement account or annuity described in section
408(a) or 408(b) of the code. The committee may request from the participant
such documents as it considers necessary or desirable to establish that the
rollover contribution satisfies the foregoing requirements."

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2. By substituting the following for subsection 4.10 of the Plan:

      "4.10. Eligible Compensation. For purposes of the plan, a participant's
`eligible compensation' for any period means the total cash remuneration paid to
him by the employers for services rendered to them as an employee, excluding
bonuses, incentive payments, and the amount of any allowance or reimbursement
for automobile or other expenses and determined without regard to reductions
made in accordance with the provisions of subsection 4.1 or section 125 or
132(f)(4) of the code. Notwithstanding the foregoing, the eligible compensation
of any participant for any plan year shall be disregarded to the extent that it
exceeds $200,000 (adjusted in accordance with section 401(a)(17) of the code),
taking into account any proration of such amount as may be required under
applicable Treasury regulations on account of a short plan year."

3. Effective as of January 1, 2001, by substituting the following for subsection
7.2 of the Plan:

      "7.2. Deduction, Crediting and Allocation of Contributions and Dividends.
Subject to the provisions of Section 8:

      (a)  Employee tax-deferred contributions, employee after-tax contributions
           and rollover contributions on behalf of a participant for any period
           shall be credited to that participant's appropriate accounts as of
           the day on which such contributions are made.

      (b)  The amount of the employer matched contributions that are made on
           behalf of a participant shall be credited to that participant's
           employer matched contribution account as of the day on which such
           contributions are made.

      (c)  As of the last day of each plan year the employer profit sharing
           contributions of each employer for that plan year shall be allocated
           among and credited to the employer profit sharing accounts of
           participants who are entitled to share in the employer profit sharing
           contribution for that year (as determined under subsection 4.4). The
           employer profit sharing contribution allocated to a participant's
           account shall be equal to the fixed dollar amount specified by the
           employer for the year or, if the employer does make a fixed
           contribution on behalf of each participant, shall be allocated pro
           rata based on the amount of the eligible compensation payable to the
           participant for that year.

      (d)  As of any accounting date which is also a dividend payment date,
           shares of Nicor stock received by the trustee as a result of a stock
           split or stock dividend shall be allocated among and credited to the
           accounts of participants whose accounts were invested in the Nicor
           stock fund as of the dividend record date to which the dividend
           payment date relates, pro rata based on the number of shares of Nicor
           stock held in the Nicor Stock fund as of the dividend record date.

      (e)  As of any accounting date which is also a dividend payment date, cash
           dividends paid on shares of Nicor stock which were held in the Nicor
           stock fund as of the dividend record date to which the dividend
           payment date relates shall be distributed to participants in
           accordance with Supplement B of the plan; provided, however, that,
           for periods on an after May 1, 2002, the trustee shall use all cash
           dividends with respect to which participants have not elected a cash
           distribution pursuant to

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           Supplement B to purchase shares of Nicor
           stock. Shares of Nicor stock purchased pursuant to the preceding
           sentence will be allocated and credited to the accounts of
           participants whose accounts were invested in the Nicor stock fund as
           of the dividend record date and who did not elect a cash distribution
           of dividends pursuant to Supplement B, pro rata based on the number
           of shares purchased by the trustee with the cash dividends.

For purposes of this Section 7, all employer contributions for any plan year
which are made after the close of the plan year will be considered to have been
made on the last day of that plan year regardless of when paid to the trustees;
provided, however, that in no event shall any contributions share in trust
earnings until actually credited to a participant's accounts.

4. By substituting the following for subsections 8.2 and 8.3, respectively, of
the Plan:

      "8.2. Compensation for Limitation/Testing Purposes. For purposes of this
Section 8, the term `section 415 compensation' shall mean with respect to any
employee or participant for any plan year the sum of:

      (a)  the section 415 compensation (as described in section 415(c)(3) of
           the code and applicable regulations) paid during that year for
           personal services actually rendered in the course of employment with
           any employer or any section 415 affiliate(as defined in subsection
           8.3); plus

      (b)  any elective contributions made on the participant's behalf for the
           year under the plan or any plan maintained by an employer or
           affiliate, which contributions are excludable from the participant's
           gross income by reason of sections 125, 402(e)(3) and section 132(f)
           of the code.

Notwithstanding the foregoing provisions of this subsection 8.2, `section 415
compensation' for any plan year shall be disregarded to the extent that it
exceeds $200,000 (adjusted in accordance with section 401(a)(17) of the code),
taking into account any proration of such amount as may be required under
applicable Treasury regulations where section 415 compensation is computed with
respect to a period of less than a full year (other than on account of mid-year
commencement or cessation of active participation in the plan)."

      8.3 Limitations on Annual Additions. Notwithstanding any other provision
of the plan, other than the provisions of this Section 8, a participant's annual
additions (as defined below) for any plan year shall not exceed an amount equal
to the lesser of:

      (a)  $40,000 (as adjusted for each plan year to take into account any
           applicable cost-of-living adjustment for that year provided by the
           Secretary of the Treasury under section 415(d) of the code); or

      (b)  100 percent of the section 415 compensation paid to the participant
           in that plan year (determined without regard to the limitations of
           section 401(a)(17) of the code).

The limitations set forth under paragraphs (a) and (b) shall be adjusted to the
extent required by subsection 8.4. The term `annual additions' means, with
respect to any participant for any plan year, the sum of the following amounts,
determined without regard to whether any such amounts (or portions thereof) are
subsequently distributed to the participant in accordance with the provisions of
subsection 8.9, 8.11, 8.13 or 8.14:

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<PAGE>

      (1)  employer contributions and forfeitures (including employee tax
           deferred contributions, which are considered to be employer
           contributions) credited to the participant's accounts for that plan
           year under this plan and each related defined contribution plan (as
           defined below);

      (2)  employee contributions (other than rollover contributions) credited
           to the participant's accounts under this plan and each related
           defined contribution plan for that plan year; and

      (3)  employer contributions allocated to any individual medical account
           (as described in section 415(l) of the code) which is maintained for
           the benefit of the participant under a related defined benefit plan
           (as defined below) and, if the participant is a key employee (as
           defined in Supplement A), any amount allocated to a related medical
           account (as defined below) maintained for the participant; provided,
           however, that the amounts described in this paragraph (3) shall be
           disregarded for purposes of the limitation set forth in paragraph (b)
           next above.

For purposes of the plan: (i) the term `related medical account' means any
account maintained by any employer or section 415 affiliate under section
419A(d) of the code to fund retiree medical benefits; (ii) the term `section 415
affiliate' means any corporation or trade or business that is, along with any
employer, a member of a controlled group of corporations or controlled group of
trades or businesses (as described in sections 414(b) and (c) of the code, as
modified by section 415(h) thereof); and (iii) the term `related defined
contribution plan' and `related defined benefit plan' mean any other defined
contribution plan and any defined benefit plan (both as defined in section
415(k) of the code), respectively, maintained by any employer or section 415
affiliate."

5. By adding the following as the last sentence of subsection 8.14 of the Plan:

"The provisions of this subsection 8.14 shall not apply for plan years beginning
after December 31, 2001."

6. By substituting the following for paragraphs (e) and (f), respectively, of
Section 9 of the Plan:

      "(e) Vested Resignation or Dismissal. The participant resigns or is
           dismissed from the employ of the employers and the affiliates before
           retirement in accordance with paragraph (a), (b) or (d) next above
           but after completing at least 3 years of service (5 years of service
           if the participant does not have at least one hour of service after
           December 31, 2001).

      (d)  Non-Vested Resignation or Dismissal. The participant resigns or is
           dismissed from the employ of the employers and the affiliates before
           retirement in accordance with paragraph (a), (b) or (d) next above
           and prior to completing at least 3 years of service (5 years of
           service if the participant does not have at least one hour of service
           after December 31, 2001)."

7. By substituting the following for subsections 10.21 and 10.22, respectively,
of the plan:

      "10.21 Direct Rollover to an Eligible Retirement Plan. Notwithstanding any
provision of the plan to the contrary that would otherwise limit a distributee's
election under this subsection 10.21, a distributee may elect, at the time and
in the manner prescribed by the committee, to have any portion

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of an "eligible
rollover distribution" (as defined in section 402(c)(4) of the code) paid
directly to an eligible retirement plan specified by the distributee in a direct
rollover. For purposes of this subsection 10.21, the following definitions shall
apply:

      (a)  An `eligible rollover distribution' means any distribution of all or
           any portion of the balance to the credit of the distributee, except
           that an eligible rollover distribution does not include: any
           distribution that is one of a series of substantially equal periodic
           payments (not less frequently than annually) made for the life (or
           life expectancy) of the distributee or the joint lives (or joint life
           expectancies) of the distributee and the distributee's designated
           beneficiary, or for a specified period of ten years or more; and any
           distribution to the extent such distribution is required under
           section 401(a)(9) of the code. A portion of a distribution shall not
           fail to be an eligible rollover distribution merely because the
           portion consists of after-tax employee contributions which are not
           includible in gross income; provided, however, that such portion may
           be transferred only to an individual retirement account or annuity
           described in section 408(a) or (b) of the code, or to a qualified
           defined contribution plan described in section 401(a) or 403(a) of
           the code that agrees to separately account for amounts so
           transferred, including separately accounting for the portion of such
           distribution which is includible in gross income and the portion of
           such distribution which is not so includible. A hardship withdrawal
           shall not constitute an eligible rollover distribution for purposes
           of the Plan.

      (b)  An `eligible retirement plan' means an individual retirement account
           described in section 408(a) of the code, an individual retirement
           annuity described in section 408(b) of the code, an annuity plan
           described in section 403(a) of the code, or a qualified trust
           described in section 401(a) of the code that accepts the
           distributee's eligible rollover distribution. For distributions
           occurring after December 31, 2001, an `eligible retirement plan' also
           includes an annuity contract described in section 403(b) of the code
           or an eligible plan under section 457(b) of the code which is
           maintained by a state, political subdivision of a state, or any
           agency or instrumentality of a state or political subdivision of a
           state and which agrees to separately account for amounts transferred
           into such plan from the Plan. The definition of eligible retirement
           plan shall also apply in the case of a distribution to a surviving
           spouse, or to a spouse or former spouse who is the alternate payee
           under a qualified domestic relations order, as defined in section
           414(p) of the code.

      (c)  A `distributee' means an employee or former employee and the
           employee's or former employee's surviving spouse and the employee's
           or former employee's spouse or former spouse who is the alternate
           payee under a qualified domestic relations order as defined in
           section 414(p) of the code.

      (d)  A `direct rollover to an eligible retirement plan' means a payment by
           the plan to the eligible retirement plan specified by the
           distributee.

      10.22 Distribution Only Upon Separation From Service. Notwithstanding any
other provision of the plan to the contrary, for periods prior to January 1,
2002, a participant may not commence distribution of his employee tax-deferred
contribution account pursuant to this Section 10, even though he has otherwise
had a termination date under Section 9, unless or until he also has a
`separation from service' within the meaning of section 401(k)(2)(B) of the
code. The foregoing restriction shall not apply, however, if the participant's
termination date occurs in connection with the sale by an employer to an
unrelated corporation of at least 85 percent of the assets of a trade or

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<PAGE>

business, or the sale of its interest in a subsidiary to an unrelated entity,
provided (a) the participant remains employed in such trade or business or by
such subsidiary after the sale, (b) the employer continues to maintain the plan
after the sale, (c) no transfer of the participant's accounts occurs or is
scheduled to occur after the sale pursuant to subsection 14.3 to a plan of such
subsidiary or of the purchaser of such assets (or any entity affiliated
therewith), and (d) the participant receives distribution of his account
balances (less any outstanding loan balances) under the plan in a lump sum by
the end of the second calendar year after the year in which the sale occurs.
Effective as of January 1, 2002, the foregoing provisions of this subsection
10.22 not apply and a Participant shall be entitled to commence distribution
upon his severance from employment, subject to other provisions of the Plan
governing distributions, other than provisions which require a separation from
service before such amounts may be distributed. The preceding sentence shall
apply as of January 1, 2002, regardless of whether the Participant's severance
from employment occurred before January 1, 2002."

8. By substituting the phrase "$200,000" for the phrase "$170,000" where the
latter phrase appears in subsection A-8 of Supplement A of the Plan.

9. By adding the following new subsection A-15 to Supplement A of the Plan
immediately after Section A-14 thereof:

"Special Rules       A-15.  This subsection shall apply for
                     purposes of determining whether the plan is a
                     top-heavy plan under section 416(g) of the
                     code for plan years beginning after December
                     31, 2001, and whether the plan satisfies the
                     minimum benefits requirements of section
                     416(c) of the code for such years. To the
                     extent applicable, this subsection supersedes
                     the foregoing provisions of this Supplement
                     A.
                     (a)  A `key employee' means any employee or former employee
                          (including any deceased employee) who at any time
                          during the plan year that includes the determination
                          date was an officer of the employers and affiliates
                          having annual compensation greater than $130,000 (as
                          adjusted under section 416(i)(1) of the code for plan
                          years beginning after December 31, 2002), a 5-percent
                          owner of the employers and affiliates, or a 1-percent
                          owner of the employer and affiliates having annual
                          compensation of more than $150,000. For this purpose,
                          annual compensation means compensation within the
                          meaning of section 415(c)(3) of the code. The
                          determination of who is a Key Employee will be made in
                          accordance with section 416(i)(1) of the code and the
                          applicable regulations and other guidance of general
                          applicability issued thereunder.
                     (b)  The following provisions shall apply for purposes of
                          determining the present values of accrued benefits and
                          the amounts of account balances of employees as of the
                          determination date.
                          (i)  The present values of accrued
                               benefits and the amounts of account balances of
                               an employee as of the determination date shall be
                               increased by the distributions made with respect
                               to the employee under

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<PAGE>

                               the plan and any plan
                               aggregated with the plan under section 416(g)(2)
                               of the code during the 1-year period ending on
                               the determination date. The preceding sentence
                               shall also apply to distributions under a
                               terminated plan which, had it not been
                               terminated, would have been aggregated with the
                               plan under section 416(g)(2)(A)(i) of the Code.
                               In the case of a distribution made for a reason
                               other than separation from service, death or
                               disability, this provision shall be applied by
                               substituting `5-year period' for `1-year period'.

                          (ii) Accrued benefits and accounts of any individual
                               who has not performed services for the employers
                               and affiliates during the 1-year period ending on
                               the determination date shall not be taken into
                               account.

                     (c)  Employer matching contributions shall be taken into
                          account for purposes of satisfying the minimum
                          contribution requirements of section 416(c)(2) of the
                          code and the plan. The preceding sentence shall apply
                          with respect to matching contributions under the plan
                          or, if the plan provides that the minimum contribution
                          requirement shall be met in another plan, such other
                          plan. Employer matching contributions that are used to
                          satisfy the minimum contribution requirements shall be
                          treated as matching contributions for purposes of the
                          actual contribution percentage test and other
                          requirements of section 401(m) of the code."

10. Effective as of May 1, 2002, by substituting the following for subsection
B-5 of Supplement B of the Plan:

"Treatment of
Cash Dividends   B-5. On and after May 1, 2002, any cash dividends paid on
                 shares of Nicor stock held by the trustee
                 in the Nicor Stock Fund shall be allocated and credited to
                 participants' accounts in accordance with Section 7.2 of the
                 plan. Notwithstanding the foregoing, a participant (or in the
                 event his death, his beneficiary) may elect to have any cash
                 dividends paid on shares of Nicor stock held by the trustee in
                 the Nicor Stock Fund distributed, in cash, as soon as
                 practicable after the accounting date ending the accounting
                 period in which the dividends are paid to the trustee (but in
                 no event more than 90 days after the close of the plan year in
                 which the dividends are paid to the trustee). Distributions
                 under this subsection B-5 on and after May 1, 2002 shall not be
                 subject to the restrictions on pre-termination withdrawals
                 described in Section 11 and shall not be considered an eligible
                 rollover distribution for purposes of subsection 10.21."


      IN WITNESS WHEREOF, the undersigned officer has caused these presents to
be signed on behalf of the Company this 18th day of December, 2002.

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                                    Birdsall Inc.

                                    By:  /s/ Robert M. Chapman
                                         ---------------------
                                    Its: VP, Pricing & Organization Support
                                         ----------------------------------


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