### Question
Can you define what diesel replacement or retrofit means?


### Answer
**Diesel replacement or retrofit** is defined as the following in *23 U.S.C. § 149*:

> a replacement or retrofit, repowering, rebuilding, after treatment, or other technology, as determined by the Administrator

#### Citation:
  - *23 U.S.C. § 149*
  - Heading: **CHAPTER 1-FEDERAL-AID HIGHWAYS**

