A sight-distance problem is associated with use of 32-in. tall concrete longitudinal barriers, specifically in certain work zone locations and at nighttime. These 32-in. tall barriers can obstruct drivers eyesight, making it difficult for drivers to detect oncoming vehicles on the other side of these barriers. To address this sight-distance problem while protecting the errant vehicles, researchers at the Texas Transportation Institute (TTI) developed a 20-in. tall low-profile portable concrete barrier (PCB) for use in low-speed work zones in the early 1990s. To address the problem for high-speed application, TTI researchers applied modifications to the 20-in. tall low-profile PCB. Researchers designed two retrofit metal rail systems to be added on top of the existing 20-in. tall low-profile PCB to address roadside and median applications. The systems successfully performed in full-scale crash testing according to NCHRP Report 350 Test Level (TL) 3 evaluation criteria. This paper describes the efforts to develop and evaluate the crashworthiness of a new low-profile PCB design for high-speed applications. The crash tests were performed following Manual for Assessing Safety Hardware (MASH) guidelines and evaluation criteria. Based on results from finite element computer simulations performed to aid design, MASH full-scale crash tests were conducted on a low-profile PCB system comprised of 26-in. tall, 30-ft long barrier segments, with a T-shaped profile. Based on constructability feedback, the sides of the barrier were formed with a negative 1:18 slope, which allows for ease of construction forming. The new low-profile PCB performed acceptably as a MASH TL-3 longitudinal barrier.