Approximate estimate is also known as a preliminary estimate.

Explanation:
When initiating a construction project, it is crucial to have an estimate of the project's cost. This estimate helps in determining the feasibility of the project and making important decisions. There are different types of estimates used in the construction industry, and one of them is the approximate estimate, which is also known as a preliminary estimate.

What is an approximate estimate?
An approximate estimate is an initial estimate made at the beginning stages of a project. It is prepared based on limited information and is used to provide a rough idea of the project's cost. This estimate is not detailed and is subject to change as more information becomes available. The purpose of an approximate estimate is to provide a preliminary budget for the project and to assess its financial viability.

Characteristics of an approximate estimate:
- It is prepared based on limited information and assumptions.
- It provides a rough estimate of the project's cost.
- It is not detailed and lacks accuracy.
- It is subject to change as more information becomes available.
- It helps in making initial decisions regarding the project's feasibility.

Importance of an approximate estimate:
- Helps in determining the financial viability of the project.
- Assists in obtaining initial funding or financing for the project.
- Guides the project team in making important decisions.
- Provides a baseline for future, more detailed estimates.

Conclusion:
The approximate estimate, also known as a preliminary estimate, is an initial estimate made at the beginning stages of a construction project. It provides a rough idea of the project's cost and helps in assessing its financial viability. As more information becomes available, the estimate can be refined and detailed estimates can be prepared.