Bay Area Rapid Transit (BART) Practice Exam 2026 - Free BART Practice Questions and Study Guide

The yellow light is commonly used as an indicator for lower priority warnings, including issues like low brake hydraulic pressure. This choice aligns with standards in many transit systems, where colors are used to signify the urgency or type of alert. In most systems, a yellow light is indicative of caution; it alerts the operator to check on a situation that might not yet be critical but could develop into a significant issue if left unaddressed. In the context of brake hydraulic pressure, the yellow light serves as a prompt for the operator to investigate and ensure that the brakes are functioning properly to maintain safety on the transit system.

Red lights typically signify critical alerts or immediate danger, often related to severe malfunctions or emergencies. Green lights usually denote that systems are operating normally and safely, while blue lights are not typically used in brake system alerts. Thus, the use of a yellow light to indicate low brake hydraulic pressure effectively conveys the necessary information for operator awareness and action.