| Explanation of Responses: |
| (1) | This Form 4 reports securities disposed of pursuant to the terms of the Amended and Restated Agreement and Plan of Merger, dated August 26, 2022 (the "Merger Agreement"), by and among Hill International, Inc. (the "Company"), Global Infrastructure Solutions Inc. ("Parent") and Liberty Acquisition Sub Inc., a wholly owned subsidiary of Parent ("Merger Sub"), a copy of which was filed as Exhibit 2.1 to the Company's Current Report on Form 8-K filed with the Securities and Exchange Commission on August 29, 2022. |
| (2) | Pursuant to the Merger Agreement, on December 27, 2022, Merger Sub was merged with and into the Company (the "Merger") with the Company surviving the Merger as the surviving corporation and an indirect wholly owned subsidiary of Parent. At the effective time of the Merger (the "Effective Time"), each share of common stock, par value $0.0001 per share, of the Company ("Common Stock") issued and outstanding immediately prior to the Effective Time (other than (A) shares of Common Stock (1) held in the treasury of the Company or (2) owned by Parent or Merger Sub or any direct or indirect wholly owned subsidiaries of Parent, Merger Sub or the Company and (B) the Appraisal Shares (as defined in the Merger Agreement), was automatically converted into the right to receive an amount in cash equal to $3.40, without interest (such amount of cash, the "Merger Consideration"). |
| (3) | Grant of deferred stock units (each, a "DSU") under the Hill International, Inc. 2017 Equity Compensation Plan. Each DSU represents a contingent right to receive one share of the Issuer's common stock. |
| (4) | On February 14, 2022, the reporting person was granted 235,602 DSUs, vesting over time in three equal portions on the first, second, and third anniversaries of the grant date, provided the reporting person is then an employee of the Company. Reported late due to the Company's failure to timely advise the reporting person that it had inadvertently omitted to timely file a Form 4 at the time when the transaction occurred. |
| (5) | Pursuant to an agreement between the reporting person and Parent, effective upon the Effective Time, these unvested Company restricted stock units ("RSUs") were assumed by Parent and converted into restricted stock units of Parent representing a contingent right to receive certain shares of Parent's capital stock. |
| (6) | Time-based vesting RSU. Each time-based vesting RSU represents a contingent right to receive one share of Common Stock. |
| (7) | Performance-based vesting RSU. Each performance-based vesting RSU represents a contingent right to receive one share of Common Stock. |
| (8) | Pursuant to an agreement between the reporting person and Parent, effective upon the Effective Time, an aggregate of 790,352 unvested DSUs were assumed by Parent and converted into restricted stock units of Parent representing a contingent right to receive certain shares of Parent's capital stock. Pursuant to the Merger Agreement, effective upon the Effective Time, an aggregate of 63,830 vested DSUs were cancelled and extinguished and, in exchange therefore, were automatically converted into the right to receive an amount in cash, without interest, equal to the product of (A) the number of shares of Common Stock subject to the such vested DSUs and (B) the Merger Consideration. |
| (9) | Time-based vesting DSU. Each time-based vesting DSU represents a contingent right to receive one share of Common Stock. |
| (10) | Performance-based vesting DSU. Each performance-based vesting DSU represents a contingent right to receive one share of Common Stock. |
| (11) | Pursuant to the Merger Agreement, effective upon the Effective Time, each Company option to purchase shares of Common Stock (each, an "Option"), that was outstanding immediately prior to the Effective Time, whether vested or unvested, became fully vested and was cancelled and extinguished and, in exchange therefore, was automatically converted into the right to receive an amount in cash, without interest, equal to the product of (A) the number of shares of Common Stock subject to such Option and (B) the excess, if any, of the Merger Consideration over any per share exercise or purchase price of such Option immediately prior to such cancellation; provided, however, that any Option that had an exercise price equal to or greater than the Merger Consideration was cancelled without any consideration therefor immediately prior to the Effective Time. |
| (12) | Pursuant to the Merger Agreement, these Options were cancelled effective upon the Effective Time without any consideration therefor because the per share exercise price of such Option ($4.00) was greater than the Merger Consideration. |
| (13) | Pursuant to the Merger Agreement, these Options were cancelled effective upon the Effective without any consideration therefor because the per share exercise price of such Option ($4.65) was greater than the Merger Consideration. |
| (14) | Pursuant to the Merger Agreement, these Options were cancelled at the Effective Time and automatically converted into the right to receive $135,000 in cash, without interest, representing the difference between the Merger Consideration and the per share exercise price of these Options ($3.13). |