Some of the results of an extensive track testing program at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech for evaluating the roll stability of commercial trucks with 33-ft A-double trailers are evaluated. The study includes straight-rail trailers with heavy and light loading conditions. Commercial trucks are more susceptible to rollovers than passenger cars because of their higher center of gravity relative to their track width. Multi-trailer articulated heavy vehicles, such as A-doubles, are particularly prone to rollovers because of their articulation and rearward amplification. Electronic stability control (ESC) has been mandated by the National Highway Safety Administration (NHSTA) for Class 8 trucks and busses since 2017. When detecting oversteer or understeer, ESC automatically activates the brakes at the correct side of the steer and/or drive axle(s) to regain steering stability. ESC, however, often cannot sense the likelihood of trailer rollover in multi-trailer articulated heavy vehicles because of the articulation between the trailers and tractors. As a result of this, trailers are often equipped with roll stability control (RSC) systems to mitigate speed-induced rollovers. Sensing the trailer lateral acceleration, RSC activates the trailer brakes to reduce speed and lower the likelihood of rollover. However, a limited number of past studies have shown that the trailer roll angle may provide an earlier indication of a pending rollover than the lateral acceleration. This study intends to provide further analysis in this regard in an effort to improve the effectiveness of RSC systems for trailers. An extensive amount of data from track testing with a 33-ft A-double under heavy and light loading is evaluated. Particular attention is given to lateral accelerations and trailer roll angles prior to rollover and relative to RSC activation time. The study's results indicate that the trailer roll angle provides a slightly earlier indication of rollover than lateral acceleration during dynamic driving conditions, potentially resulting in a timelier activation of RSC. Of course, detecting the roll angle is often more challenging than lateral acceleration, which can be detected with an accelerometer. Additionally, the roll angle measurement may be subjected to errors and possibly unwanted RSC engagement. The study's results further indicate that the trailer-based RSC systems effectively mitigate rollovers in both quasi-steady-state and dynamic driving conditions. / Master of Science / Some of the results of an extensive track testing program at the Center for Vehicle Systems and Safety (CVeSS) at Virginia Tech for evaluating the roll stability of commercial trucks with 33-ft A-double trailers are evaluated. "33-ft A-doubles" commonly refer to a commercial truck that has a tractor with two trailers (in this case 33-ft in length) that are connected by an A-dolly. Their modularity and ease of connecting and disconnecting at various drop stations have made such commercial vehicles a common scene on U.S. highways due to the proliferation of e-commerce cargo. Compared to a single-unit or tractor semi-trailer combination, the double- or triple-trailer configurations offer several logistical benefits that make them more advantageous. The multi-trailer vehicles can carry more cargo per driver, lowering driver, fuel, and equipment costs significantly. There are, however, some challenges to operating multi-trailer articulated vehicles. On average, their accidents are more expensive than single-trailer or single-unit trucks. Additionally, they are more susceptible to rolling over and causing property damage, injuries, and at times fatalities. To reduce rollovers, systems with automated braking, called roll stability control (RSC), are often installed on the trailers. RSC applies the trailer brakes if it senses that the vehicle speed — the primary cause of most commercial vehicle accidents — exceeds the safe limit for negotiating a turn. In this study, we intend to evaluate the effectiveness of roll stability control (RSC) systems for reducing the likelihood of speed-induced rollovers. We will also explore ways of improving their performance. Namely, we will evaluate whether sensing the lateral acceleration of the trailer or its roll angle would provide a better means for timely activation of RSC. The study's results indicate that, although more challenging to measure, the trailer roll angle provides a slightly sooner indication of a pending rollover than lateral acceleration. The results also suggest that RSC systems vastly reduce the number of speed-induced rollovers in trucks with 33-ft A-double trailers under different trailer configurations and cargo weights.