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                                                                   Exhibit 10.53

                                 TRUST AGREEMENT

                                     BETWEEN

                            SAFETY INSURANCE COMPANY

                     [                                     ]

                                       AND

                        FIDELITY MANAGEMENT TRUST COMPANY

                                   ----------

                     [                                     ]

                                      TRUST

                                                                          [SEAL]

                             Dated as of [1/1], 2004

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                                TABLE OF CONTENTS

<Table>
<Caption>
SECTION                                                                   PAGE
-------                                                                   ----
<S>                                                                         <C>
1  DEFINITIONS ..............................................................2

2  TRUST ....................................................................3
   (a) Establishment
   (b) Grantor Trust
   (c) Trust Assets
   (d) Non-Assignment

3  PAYMENTS TO SPONSOR ......................................................4

4  DISBURSEMENT .............................................................4
   (a) Directions from Administrator
   (b) Limitations

5  INVESTMENT OF TRUST ......................................................5
   (a) Selection of Investment Options
   (b) Available Investment Options
   (c) Investment Directions
   (d) Funding Mechanism
   (e) Mutual Funds
   (f) Trustee Powers

6  RECORDKEEPING AND ADMINISTRATIVE SERVICES TO BE PERFORMED ................7
   (a) General
   (b) Accounts
   (c) Inspection and Audit
   (d) Notice of Plan Amendment
   (e) Returns, Reports and Information

7  COMPENSATION AND EXPENSES ................................................9

8  DIRECTIONS AND INDEMNIFICATION ...........................................9
   (a) Identity of Administrator
   (b) Directions from Administrator
   (c) Directions from Participants
   (d) Indemnification
   (e) Survival

9  RESIGNATION OR REMOVAL OF TRUSTEE .......................................10
   (a) Resignation and Removal
   (b) Termination
   (c) Notice Period
   (d) Transition Assistance
   (e) Failure to Appoint Successor

10 SUCCESSOR TRUSTEE .......................................................11
   (a) Appointment
   (b) Acceptance
   (c) Corporate Action
</Table>

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                                TABLE OF CONTENTS
                                   (CONTINUED)

<Table>
<Caption>
SECTION                                                                   PAGE
-------                                                                   ----
<S>                                                                         <C>
11 RESIGNATION, REMOVAL, AND TERMINATION NOTICES ...........................11

12 DURATION ................................................................11

13 INSOLVENCY OF SPONSOR ...................................................12

14 AMENDMENT OR MODIFICATION ...............................................13

15 ELECTRONIC SERVICES .....................................................13

16 GENERAL .................................................................14
   (a) Performance by Trustee, its Agent or Affiliates
   (b) Entire Agreement
   (c) Waiver
   (d) Successors and Assigns
   (e) Partial Invalidity
   (f) Section Headings

17 ASSIGNMENT ..............................................................15

18 FORCE MAJEURE ...........................................................15

19 CONFIDENTIALITY .........................................................16

20 GOVERNING LAW ...........................................................16
   (a) Massachusetts Law Controls
   (b) Trust Agreement Controls
</Table>

                                       ii
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     TRUST AGREEMENT, dated as of the 1ST day of JANUARY 2004, between SAFETY
INSURANCE COMPANY, a MA corporation, having an office at 20 CUSTOM HOUSE ST.
BOSTON, MA (the "Sponsor"), and FIDELITY MANAGEMENT TRUST COMPANY, a
Massachusetts trust company, having an office at 82 Devonshire Street, Boston,
Massachusetts 02109 (the "Trustee").

                                   WITNESSETH:

     WHEREAS, the Sponsor is the sponsor of the SAFETY INSURANCE COMPANY
EXECUTIVE INCENTIVE COMPENSATION PLAN (the "Plan"); and

     WHEREAS, the Sponsor wishes to establish an irrevocable trust and to
contribute to the trust assets that shall be held therein, subject to the claims
of Sponsor's creditors in the event of Sponsor's Insolvency, as herein defined,
until paid to Participants and their beneficiaries in such manner and at such
times as specified in the Plan; and

     WHEREAS, it is the intention of the parties that this Trust shall
constitute an unfunded arrangement and shall not affect the status of the Plan
as an unfunded plan maintained for the purpose of providing deferred
compensation for a select group of management or highly compensated employees
for purposes of Title I of the Employee Retirement Income Security Act of 1974
("ERISA"); and

     WHEREAS, it is the intention of the Sponsor to make contributions to the
trust to provide itself with a source of funds to assist it in the meeting of
its liabilities under the Plan; and

     WHEREAS, the Trustee is willing to hold and invest the aforesaid plan
assets in trust among several investment options selected by the Sponsor; and

     WHEREAS, the Sponsor wishes to have the Trustee perform certain ministerial
recordkeeping and administrative functions under the Plan; and

     WHEREAS, SAFETY INSURANCE COMPANY (the "Administrator") is the
administrator of the Plan; and

     WHEREAS, the Trustee is willing to perform recordkeeping and administrative
services for the Plan if the services are purely ministerial in nature and are
provided within a framework of plan provisions, guidelines and interpretations
conveyed in writing to the Trustee by the Administrator.

                                        1
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     NOW, THEREFORE, in consideration of the foregoing premises and the mutual
covenants and agreements set forth below, the Sponsor and the Trustee agree as
follows:

SECTION 1. DEFINITIONS. The following terms as used in this Trust Agreement have
the meaning indicated unless the context clearly requires otherwise:

(a)  "ADMINISTRATOR" shall mean, with respect to the Plan, the person or entity
     which is the "administrator" of such Plan.

(b)  "AGREEMENT" shall mean this Trust Agreement, as the same may be amended and
     in effect from time to time.

(c)  "BUSINESS DAY" shall mean any day on which the New York Stock Exchange
     (NYSE) is open.

(d)  "CODE" shall mean the Internal Revenue Code of 1986, as it has been or may
     be amended from time to time.

(e)  "ERISA" shall mean the Employee Retirement Income Security Act of 1974, as
     it has been or may be amended from time to time.

(f)  "FIDELITY MUTUAL FUND" shall mean any investment company advised by
     Fidelity Management & Research Company or any of its affiliates.

(g)  "MUTUAL FUND" shall refer both to Fidelity Mutual Funds and Non-Fidelity
     Mutual Funds.

(h)  "NON-FIDELITY MUTUAL FUND" shall mean certain investment companies not
     advised by Fidelity Management & Research Company or any of its affiliates.

(i)  "PARTICIPANT" shall mean, with respect to the Plan, any employee (or former
     employee) with an account under the Plan, which has not yet been fully
     distributed and/or forfeited, and shall include the designated
     beneficiary(ies) with respect to the account of any deceased employee (or
     deceased former employee) until such account has been fully distributed
     and/or forfeited.

(j)  "Permissible Investment" shall mean the investments specified by the
     Employer as available for investment of assets of the Trust and agreed to
     by the Trustee and the Prototype Sponsor. The Permissible Investments under
     the Plan shall be listed in the Service Agreement.

(k)  "PLAN" shall mean the SAFETY INSURANCE COMPANY EXECUTIVE INCENTIVE
     COMPENSATION PLAN.

(l)  "RECONCILIATION PERIOD" shall mean the period beginning on the date of the
     initial transfer of assets to the Trust and ending on the date of the
     completion of the reconciliation of Participant records.

(m)  "REPORTING DATE" shall mean the last day of each calendar quarter, the date
     as of which the Trustee resigns or is removed pursuant to this Agreement
     and the date as of which this Agreement terminates pursuant to Section 9
     hereof.

(n)  "SERVICE AGREEMENT" shall mean the agreement between the Trustee and the
     Sponsor for the Trustee, through certain affiliates and related companies,
     to provide administrative and recordkeeping services for the Plan.

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(o)  "SPONSOR" shall mean SAFETY INSURANCE COMPANY, a MA corporation, or any
     successor to all or substantially all of its businesses which, by
     agreement, operation of law or otherwise, assumes the responsibility of the
     Sponsor under this Agreement.

(p)  "TRUST" shall mean the SAFETY INSURANCE COMPANY EXECUTIVE INCENTIVE
     COMPENSATION PLAN Trust, being the trust established by the Sponsor and
     the Trustee pursuant to the provisions of this Agreement.

(q)  "TRUSTEE" shall mean Fidelity Management Trust Company, a Massachusetts
     trust company and any successor to all or substantially all of its trust
     business. The term Trustee shall also include any successor trustee
     appointed pursuant to this agreement to the extent such successor agrees to
     serve as Trustee under this Agreement.

SECTION 2. TRUST.

             (a)  ESTABLISHMENT. The Sponsor hereby establishes the Trust, with
the Trustee. The Trust shall consist of an initial contribution of money or
other property acceptable to the Trustee in its sole discretion, made by the
Sponsor or transferred from a previous trustee under the Plan, such additional
sums of money as shall from time to time be delivered to the Trustee under the
Plan, all investments made therewith and proceeds thereof, and all earnings and
profits thereon, less the payments that are made by the Trustee as provided
herein, without distinction between principal and income. The Trustee hereby
accepts the Trust on the terms and conditions set forth in this Agreement. In
accepting this Trust, the Trustee shall be accountable for the assets received
by it, subject to the terms and conditions of this Agreement.

             (b)  GRANTOR TRUST. The Trust is intended to be a grantor trust, of
which the Sponsor is the grantor, within the meaning of subpart E, part 1,
subchapter J, chapter 1, subtitle A of the Code, as amended, and shall be
construed accordingly.

             (c)  TRUST ASSETS. The principal of the Trust, and any earnings
thereon shall be held separate and apart from other funds of the Sponsor and
shall be used exclusively for the uses and purposes of Participants and general
creditors as herein set forth. Participants and their beneficiaries shall have
no preferred claim on, or any beneficial ownership interest in, any assets of
the Trust. Any rights created under the Plan and this Trust Agreement shall be
mere unsecured contractual rights of Participants and their beneficiaries
against the Sponsor. Any assets held by the Trust will be subject to the claims
of the Sponsor's general creditors under federal and state law in the event of
Insolvency, as defined in this Agreement.

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             (d)  NON-ASSIGNMENT. Benefit payments to Participants and their
beneficiaries funded under this Trust may not be anticipated, assigned (either
at law or in equity), alienated, pledged, encumbered, or subjected to
attachment, garnishment, levy, execution, or other legal or equitable process.

SECTION 3. PAYMENTS TO SPONSOR. Except as provided under this Agreement, the
Sponsor shall have no right to retain or divert to others any of the Trust
assets before all payment of benefits have been made to the Participants and
their beneficiaries pursuant to the terms of the Plan.

SECTION 4. DISBURSEMENTS.

             (a)  DIRECTIONS FROM ADMINISTRATOR.

                  (i)   If it is indicated in the Service Agreement that the
Trustee will make distributions of Plan benefits directly to Participants and
beneficiaries, the Trustee shall disburse monies to Participants and their
beneficiaries for benefit payments in the amounts that the Administrator directs
from time to time in writing. The Trustee shall have no responsibility to
ascertain whether the Administrator's direction compiles with the terms of the
Plan or of any applicable law. The Trustee shall be responsible for Federal or
State income tax reporting or withholding with respect to such Plan benefits.
The Trustee shall not be responsible for FICA (Social Security and Medicare),
any Federal or State unemployment or local tax with respect to Plan
distributions.

                  (ii)  If it is indicated in the Service Agreement that the
Sponsor shall be responsible for making distributions of benefits to
Participants and beneficiaries, then the Trustee shall disburse monies to the
Administrator for benefit payments in the amounts that the Administrator directs
from time to time in writing. The Trustee shall have no responsibility to
ascertain whether the Administrator's direction complies with the terms of the
Plan or any applicable law. The Trustee shall not be responsible for: (1) making
benefit payments to Participants under the Plan, (2) any Federal, State or local
income tax reporting or withholding with respect to such Plan benefits, and (3)
FICA (Social Security and Medicare) or any Federal or State unemployment tax
with respect to Plan distributions.

             (b)  LIMITATIONS. The Trustee shall not be required to make any
disbursement in excess of the net realizable value of the assets of the Trust at
the time of the disbursement. The Trustee shall not be required to make any
disbursement in cash unless the Administrator has provided a written direction
as to the assets to be converted to cash for the purpose of making the
disbursement.

SECTION 5. INVESTMENT OF TRUST.

                                        4
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             (a)  SELECTION OF INVESTMENT OPTIONS. The Trustee shall have no
responsibility for the selection of investment options under the Trust and shall
not render investment advice to any person in connection with the selection of
such options.

             (b)  AVAILABLE INVESTMENT OPTIONS. The Sponsor shall direct the
Trustee as to what investment options the Trust shall be invested in (i) during
the Reconciliation Period, and (ii) following the Reconciliation Period, subject
to the following limitations. The Sponsor may determine to offer as investment
options only Permissible Investments as described in the Service Agreement;
provided, however, that the Trustee shall not be considered a fiduciary with
investment discretion. The Sponsor may add or remove investment options with the
consent of the Trustee and upon mutual amendment of the Service Agreement to
reflect such additions.

             (c)  INVESTMENT DIRECTIONS. In order to provide for an accumulation
of assets comparable to the contractual liabilities accruing under the Plan, the
Sponsor may direct the Trustee in writing to invest the assets held in the Trust
to correspond to the hypothetical investments made for Participants in
accordance with their direction under the Plan.

             (d)  The Sponsor's designation of available investment options
under paragraphs (a) and (b) above, the maintenance of accounts for each Plan
Participant and the crediting of investments to such accounts, and the exercise
by Participants of any powers relating to investments under this Section 5 are
solely for the purpose of providing a mechanism for measuring the obligation of
the Sponsor to any particular Participant under the applicable Plan. As further
provided in this Agreement, no Participant or beneficiary will have any
preferential claim to or beneficial ownership interest in any asset or
investment held in the Trust, and the rights of any participant and his or her
beneficiaries under the applicable Plan and this Agreement are solely those of
an unsecured general creditor of the Sponsor with respect to the benefits of the
Participant under the Plan.

             (e)  MUTUAL FUNDS. The Sponsor hereby acknowledges that it has
received from the Trustee a copy of the prospectus for each Mutual Fund selected
by the Sponsor as a Plan investment option. Trust investments in Mutual Funds
shall be subject to the following limitations:

                  (i)   EXECUTION OF PURCHASES AND SALES. Purchases and sales of
Permissible Investments (other than for Exchanges) shall be made on the date on
which the Trustee receives from the Sponsor in good order all information and
documentation necessary to accurately effect such purchases and sales (or in the
case of a purchase, the subsequent date on which the Trustee has received a wire
transfer of funds necessary to make such purchase). Exchanges of Permissible
Investments shall be made on the same

                                        5
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Business Day that the Trustee receives a proper direction if received before
market close (generally 4:00 p.m. eastern time); if the direction is received
after market close (generally 4:00 p.m. eastern time), the exchange shall be
made the following Business Day.

                  (ii)  VOTING. At the time of mailing of notice of each annual
or special stockholder's meeting of any Mutual Fund, the Trustee shall send a
copy of the notice and all proxy solicitation materials to the Sponsor, together
with a voting direction form for return to the Trustee or its designee. The
Trustee shall vote the shares held in the Trust in the manner as directed by the
Sponsor. The Trustee shall not vote shares for which it has received no
corresponding directions from the Sponsor. The Sponsor shall also have the right
to direct the Trustee as to the manner in which all shareholder rights, other
than the right to vote, shall be exercised. The Trustee shall have no duty to
solicit directions from the Sponsor.

             (f)  TRUSTEE POWERS. The Trustee shall have the following powers
and authority:

                  (i)   Subject to paragraphs (b), (c) and (d) of this Section
5, to sell, exchange, convey, transfer, or otherwise dispose of any property
held in the Trust, by private contract or at public auction. No person dealing
with the Trustee shall be bound to see to the application of the purchase money
or other property delivered to the Trustee or to inquire into the validity,
expediency, or propriety of any such sale or other disposition.

                  (ii)  To cause any securities or other property held as part
of the Trust to be registered in the Trustee's own name, in the name of one or
more of its nominees, or in the Trustee's account with the Depository Trust
Company of New York and to hold any investments in bearer form, but the books
and records of the Trustee shall at all times show that all such investments are
part of the Trust.

                  (iii) To keep that portion of the Trust in cash or cash
balances as the Sponsor or Administrator may, from time to time, deem to be in
the best interest of the Trust.

                  (iv)  To make, execute, acknowledge, and deliver any and all
documents of transfer or conveyance and to carry out the powers herein granted.

                                        6
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             (b)  ACCOUNTS. The Trustee shall keep accurate accounts of all
investments, receipts, disbursements, and other transactions hereunder, and
shall report the value of the assets held in the Trust as of the last day of
each fiscal quarter of the Plan and, if not on the last day of a fiscal quarter,
the date on which the Trustee resigns or is removed as provided in this
Agreement or is terminated as provided in this Agreement. Within thirty (30)
days following each Reporting Date or within sixty (60) days in the case of a
Reporting Date caused by the resignation or removal of the Trustee, or the
termination of this Agreement, the Trustee shall file with the Administrator a
written account setting forth all investments, receipts, disbursements, and
other transactions effected by the Trustee between the Reporting Date and the
prior Reporting Date, and setting forth the value of the Trust as of the
Reporting Date. Except as otherwise required under applicable law, upon the
expiration of six (6) months from the date of filing such account with the
Administrator, the Trustee shall have no liability or further accountability to
anyone with respect to the propriety of its acts or transactions shown in such
account, except with respect to such acts or transactions as to which the
Sponsor shall within such six (6) month period file with the Trustee written
objections.

             (c)  INSPECTION AND AUDIT. All records generated by the Trustee in
accordance with paragraphs (a) and (b) shall be open to inspection and audit,
during the Trustee's regular business hours prior to the termination of this
Agreement, by the Administrator or any person designated by the Administrator.
Upon the resignation or removal of the Trustee or the termination of this
Agreement, the Trustee shall provide to the Administrator, at no expense to the
Sponsor, in the format regularly provided to the Administrator, a statement of
each Participant's accounts as of the resignation, removal, or termination, and
the Trustee shall provide to the Administrator or the Plan's new recordkeeper
such further records as are reasonable, at the Sponsor's expense.

             (d)  EFFECT OF PLAN AMENDMENT. The Trustee's provision of the
recordkeeping and administrative services set forth in this Section shall be
conditioned on the Sponsor delivering to the Trustee a copy of any amendment to
the Plan as soon as administratively feasible following the amendment's
adoption, and on the Administrator providing the Trustee on a timely basis with
all the information the Administrator deems necessary for the Trustee to perform
the recordkeeping and administrative services and such other information as the
Trustee may reasonably request.

             (e)  RETURNS, REPORTS AND INFORMATION. Except as set forth in the
Service Agreement, the Administrator shall be responsible for the preparation
and filing of all returns, reports, and information required of the Trust or
Plan by law. The Trustee shall provide the Administrator with such information
as the Administrator may reasonably request to make these filings. The
Administrator shall also be responsible for making any disclosures to
Participants required by law.

                                        8
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SECTION 7. COMPENSATION AND EXPENSES. Sponsor shall pay to Trustee, within
thirty (30) days of receipt of the Trustee's bill, the fees for services in
accordance with the Service Agreement. All fees for services are specifically
outlined in the Service Agreement and are based on any assumptions identified
therein.

             All reasonable expenses of plan administration as shown on the
Service Agreement, as amended from time to time, shall be a charge against and
paid from the appropriate plan Participants' accounts, except to the extent such
amounts are paid by the Plan Sponsor in a timely manner.

             All expenses of the Trustee relating directly to the acquisition
and disposition of investments constituting part of the Trust, and all taxes of
any kind whatsoever that may be levied or assessed under existing or future laws
upon or in respect of the Trust or the income thereof, shall be a charge against
and paid from the appropriate Participants' accounts.

SECTION 8. DIRECTIONS AND INDEMNIFICATION.

             (a)  IDENTITY OF ADMINISTRATOR. The Trustee shall be fully
protected in relying on the fact that the Administrator under the Plan is the
individual or persons named as such above or such other individuals or persons
as the Sponsor may notify the Trustee in writing.

             (b)  DIRECTIONS FROM ADMINISTRATOR. Whenever the Administrator
provides a direction to the Trustee, the Trustee shall not be liable for any
loss, or by reason of any breach, arising from the direction if the direction is
contained in a writing (or is oral and immediately confirmed in a writing)
signed by any individual whose name and signature have been submitted (and not
withdrawn) in writing to the Trustee by the Administrator in the manner
described in the Service Agreement, provided the Trustee reasonably believes the
signature of the individual to be genuine. Such direction may be made via
electronic data transfer ("EDT") in accordance with procedures agreed to by the
Administrator and the Trustee; provided, however, that the Trustee shall be
fully protected in relying on such direction as if it were a direction made in
writing by the Administrator. The Trustee shall have no responsibility to
ascertain any direction's (i) accuracy, (ii) compliance with the terms of the
Plan or any applicable law, or (iii) effect for tax purposes or otherwise.

             (c)  DIRECTIONS FROM PARTICIPANTS. The Trustee shall not be liable
for any loss, which arises, from any Participant's exercise or non-exercise of
rights under this Agreement over the hypothetical assets in the Participant's
accounts.

                                        9
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             (c)  FAILURE TO APPOINT SUCCESSOR. If, by the termination date, the
Sponsor has not notified the Trustee in writing as to the individual or entity
to which the assets and cash are to be transferred and delivered, the Trustee
may bring an appropriate action or proceeding for leave to deposit the assets
and cash in a court of competent jurisdiction. The Trustee shall be reimbursed
by the Sponsor for all costs and expenses of the action or proceeding including,
without limitation, reasonable attorneys' fees and disbursements.

SECTION 10. SUCCESSOR TRUSTEE.

             (a)  APPOINTMENT. If the office of Trustee becomes vacant for any
reason, the Sponsor may in writing appoint a successor trustee under this
Agreement. The successor trustee shall have all of the rights, powers,
privileges, obligations, duties, liabilities, and immunities granted to the
Trustee under this Agreement. The successor trustee and predecessor trustee
shall not be liable for the acts or omissions of the other with respect to the
Trust.

             (b)  ACCEPTANCE. When the successor trustee accepts its appointment
under this Agreement, title to and possession of the Trust assets shall
immediately vest in the successor trustee without any further action on the part
of the predecessor trustee. The predecessor trustee shall execute all
instruments and do all acts that reasonably may be necessary or reasonably may
be requested in writing by the Sponsor or the successor trustee to vest title to
all Trust assets in the successor trustee or to deliver all Trust assets to the
successor trustee.

             (c)  CORPORATE ACTION. Any successor of the Trustee or successor
trustee, through sale or transfer of the business or trust department of the
Trustee or successor trustee, or through reorganization, consolidation, or
merger, or any similar transaction, shall, upon consummation of the transaction,
become the successor trustee under this Agreement.

SECTION 11. RESIGNATION, REMOVAL, AND TERMINATION NOTICES. All notices of
resignation, removal, or termination under this Agreement must be in writing and
mailed to the party to which the notice is being given by certified or
registered mail, return receipt requested, to the Sponsor at the address
designated in the Service Agreement, and to the Trustee c/o John M. Kimpel,
Fidelity Investments, 82 Devonshire Street, F7A, Boston, Massachusetts 02109, or
to such other addresses as the parties have notified each other of in the
foregoing manner.

SECTION 12. DURATION. This Trust shall continue in effect without limit as to
time, subject, however, to the provisions of this Agreement relating to
amendment, modification, and termination thereof.

                                       11
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SECTION 13. INSOLVENCY OF SPONSOR.

             (a)  Trustee shall cease disbursement of funds for payment of
benefits to Participants and their beneficiaries if the Sponsor is Insolvent.
Sponsor shall be considered "Insolvent" for purposes of this Trust Agreement if
(i) Sponsor is unable to pay its debts as they become due, or (ii) Sponsor is
subject to a pending proceeding as a debtor under the United States Bankruptcy
Code.

             (b)  All times during the continuance of this Trust, the principal
and income of the Trust shall be subject to claims of general creditors of the
Sponsor under federal and state law as set forth below.

                  (i)   The Board of Directors and the Chief Executive Officer
of the Sponsor shall have the duty to inform Trustee in writing of Sponsor's
Insolvency. If a person claiming to be a creditor of the Sponsor alleges in
writing to Trustee that Sponsor has become Insolvent, Trustee shall determine
whether Sponsor is Insolvent and, pending such determination, Trustee shall
discontinue disbursements for payment of benefits to Participants or their
beneficiaries.

                  (ii)  Unless Trustee has actual knowledge of Sponsor's
Insolvency, or has received notice from Sponsor or a person claiming to be a
creditor alleging that Sponsor is Insolvent, Trustee shall have no duty to
inquire whether Sponsor is Insolvent. Trustee may in all events rely on such
evidence concerning Sponsor's solvency as may be furnished to Trustee and that
provides Trustee with a reasonable basis for making a determination concerning
Sponsor's solvency.

                  (iii) If at any time Trustee has determined that Sponsor is
Insolvent, Trustee shall discontinue disbursements for payments to Participants
or their beneficiaries and shall hold the assets of the Trust for the benefit of
Sponsor's general creditors. Nothing in this Trust Agreement shall in any way
diminish any rights of Participants or their beneficiaries to pursue their
rights as general creditors of Sponsor with respect to benefits due under the
Plan or otherwise.

                  (iv)  Trustee shall resume disbursement for the payment of
benefits to Plan Participants or their beneficiaries in accordance with this
Agreement only after Trustee has determined that Sponsor is not Insolvent (or is
no longer Insolvent).

                                       12
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             (c)  All Electronic Products shall be provided to the Sponsor
without any express or implied legal warranties or acceptance of legal liability
by the Trustee, and all Electronic Services shall be provided to the Sponsor
without acceptance of legal liability related to or arising out of the
electronic nature of the delivery or provision of such Services. Except as
otherwise stated in this Agreement, no rights are conveyed to any property,
intellectual or tangible, associated with the contents of the Electronic
Products or Services and related material. The Trustee hereby grants to the
Sponsor a non-exclusive, non-transferable revocable right and license to use the
Electronic Products and Services in accordance with the terms and conditions of
this Agreement.

             (d)  To the extent that any Electronic Products or Services utilize
Internet services to transport data or communications, the Trustee will take,
and Sponsor agrees to follow, reasonable security precautions, however, the
Trustee disclaims any liability for interception of any such data or
communications. The Trustee reserves the right not to accept data or
communications transmitted via electronic media by the Sponsor or a third party
if it determines that the media does not provide adequate data security, or if
it is not administratively feasible for the Trustee to use the data security
provided. The Trustee shall not be responsible for, and makes no warranties
regarding access, speed or availability of Internet or network services, or any
other service required for electronic communication. The Trustee shall not be
responsible for any loss or damage related to or resulting from any changes or
modifications to the Electronic Products or Services after delivering it to the
Sponsor.

SECTION 16. GENERAL.

             (a)  PERFORMANCE BY TRUSTEE, ITS AGENTS OR AFFILIATES. The Sponsor
acknowledges and authorizes that the services to be provided under this
Agreement shall be provided by the Trustee, its agents or affiliates, including
but not limited to Fidelity Investments Institutional Operations Company, Inc.
or its successor, and that certain of such services may be provided pursuant to
one or more other contractual agreements or relationships.

             (b)  ENTIRE AGREEMENT. This Agreement contains all of the terms
agreed upon between the parties with respect to the subject matter hereof.

             (c)  WAIVER. No waiver by either party of any failure or refusal to
comply with an obligation hereunder shall be deemed a waiver of any other or
subsequent failure or refusal to so comply.

             (d)  SUCCESSORS AND ASSIGNS. The stipulations in this Agreement
shall inure to the benefit of, and shall bind, the successors and assigns of the
respective parties.

                                       14
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             (e)  PARTIAL INVALIDITY. If any term or provision of this Agreement
or the application thereof to any person or circumstances shall, to any extent,
be invalid or unenforceable, the remainder of this Agreement, or the application
of such term or provision to persons or circumstances other than those as to
which it is held invalid or unenforceable, shall not be affected thereby, and
each term and provision of this Agreement shall be valid and enforceable to the
fullest extent permitted by law.

             (f)  SECTION HEADINGS. The headings of the various sections and
subsections of this Agreement have been inserted only for the purposes of
convenience and are not part of this Agreement and shall not be deemed in any
manner to modify, explain, expand or restrict any of the provisions of this
Agreement.

SECTION 17. ASSIGNMENT. This Agreement, and any of its rights and obligations
hereunder, may not be assigned by any party without the prior written consent of
the other party(ies), and such consent may be withheld in any party's sole
discretion. Notwithstanding the foregoing, Trustee may assign this Agreement in
whole or in part, and any of its rights and obligations hereunder, to a
subsidiary or affiliate of Trustee without consent of the Sponsor. All
provisions in this Agreement shall extend to and be binding upon the parties
hereto and their respective successors and permitted assigns.

SECTION 18. FORCE MAJEURE. No party shall be deemed in default of this Agreement
to the extent that any delay or failure in performance of its obligation(s)
results, without its fault or negligence, from any cause beyond its reasonable
control, such as acts of God, acts of civil or military authority, embargoes,
epidemics, war, riots, insurrections, fires, explosions, earthquakes, floods,
unusually severe weather conditions, power outages or strikes. This clause shall
not excuse any of the parties to the Agreement from any liability which results
from failure to have in place reasonable disaster recovery and safeguarding
plans adequate for protection of all data each of the parties to the Agreement
are responsible for maintaining for the Plan.

                                       15
<Page>

SECTION 19. CONFIDENTIALITY. Both parties to this Agreement recognize that in
the course of implementing and providing the services described herein, each
party may disclose to the other confidential information. All such confidential
information, individually and collectively, and other proprietary information
disclosed by either party shall remain the sole property of the party disclosing
the same, and the receiving party shall have no interest or rights with respect
thereto if so designated by the disclosing party to the receiving party. Each
party agrees to maintain all such confidential information in trust and
confidence to the same extent that it protects its own proprietary information,
and not to disclose such confidential information to any third party without the
written consent of the other party. Each party further agrees to take all
reasonable precautions to prevent any unauthorized disclosure of confidential
information. In addition, each party agrees not to disclose or make public to
anyone, in any manner, the terms of this Agreement, except as required by law,
without the prior written consent of the other party.

SECTION 20. GOVERNING LAW.

             (a)  MASSACHUSETTS LAW CONTROLS. This Agreement is being made in
the Commonwealth of Massachusetts, and the Trust shall be administered as a
Massachusetts trust. The validity, construction, effect, and administration of
this Agreement shall be governed by and interpreted in accordance with the laws
of the Commonwealth of Massachusetts, except to the extent those laws are
superseded under Section 514 of ERISA.

             (b)  TRUST AGREEMENT CONTROLS. The Trustee is not a party to the
Plan, and in the event of any conflict between the provisions of the Plan and
the provisions of this Agreement, the provisions of this Agreement shall
control.

                                       16
<Page>

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed
by their duly authorized officers as of the day and year first above written.


                     PLAN SPONSOR NAME: SAFETY INSURANCE COMPANY
                                        ----------------------------------------


                                        BY:    /s/ William J. Begley, Jr
                                               ---------------------------------

                                        NAME:  WILLIAM J. BEGLEY, JR
                                               ---------------------------------

                                        TITLE: VP, TREASURER, CFO
                                               ---------------------------------

                                        DATE:      12/11/03
                                               ---------------------------------


                                        FIDELITY MANAGEMENT TRUST COMPANY


                                        BY:        /s/ Glen J. Kindness
                                               ---------------------------------

                                        NAME:        Glen J. Kindness
                                               ---------------------------------

                                        TITLE:     Authorized Signatory
                                               ---------------------------------

                                        DATE:      December 19-2003
                                               ---------------------------------

                                       17
<Page>

IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be executed
by their duly authorized officers as of the day and year first above written.


                     PLAN SPONSOR NAME: SAFETY INSURANCE COMPANY
                                        ----------------------------------------


                                        BY:    /s/ William J. Begley, Jr
                                               ---------------------------------

                                        NAME:  WILLIAM J. BEGLEY, JR
                                               ---------------------------------

                                        TITLE: VP, TREASURER, CFO
                                               ---------------------------------

                                        DATE:      12/11/03
                                               ---------------------------------


                                        FIDELITY MANAGEMENT TRUST COMPANY


                                        BY:        /s/ Glen J. Kindness
                                               ---------------------------------

                                        NAME:        Glen J. Kindness
                                               ---------------------------------

                                        TITLE:     Authorized Signatory
                                               ---------------------------------

                                        DATE:      December 19, 2003
                                               ---------------------------------

                                       18