12/23/2023 0 Comments Traffic jamIn addition to managing speed, most TJA systems also utilize lane-centering technology to keep the vehicle from drifting. In the same vein, most TJA systems disengage if the driver’s hands leave the wheel for too long. This “reawakening” of the system helps ensure the driver is paying attention to the overall traffic conditions and not simply tuning out because the car has been resting for an extended time. However, most TJA systems require that the driver re-engage the system with a light touch to the gas pedal if the car has been completely still for more than 30 seconds. TJA will also bring the vehicle to a complete stop and then resume driving when the traffic ahead moves. The TJA system will accelerate and decelerate the vehicle on its own without driver intervention. In other words, the driver does not have to operate the gas or brake pedals through heavy traffic actively. But as opposed to adaptive cruise control’s goal of maintaining highway cruising velocity, TJA takes effect when a car approaches slowed traffic and slows to a crawl.ĭesigned to operate at speeds under 40 miles per hour, TJA will adjust the vehicle’s following distance based on the stop-and-go traffic ahead. It utilizes a front-mounted radar unit, cameras, and sensors to detect vehicles ahead and automatically adjust to their speeds. To help make heavy traffic more bearable, TJA essentially acts as a low-speed version of adaptive cruise control. Making allowance for the gap between vehicles, and using a created unit of "length occupied by a vehicle in a traffic jam", would decrease all these estimates.How does TJA work? - Find the best car deals! This would amount to $38,760/13.5 \approx 2900$ for a total of $4,400$ vehicles in the traffic jam. For example, if there are $1500$ trucks, they would occupy $1500 \times 16.4 = 24,600$ ft, leaving $38,760$ ft for the sedans. As in the commentary, note that if different conventions are made about how many lanes are involved in the context, this might affect this estimate by a factor of 2 or 4.Ī more reasonable assumption would be that there are both trucks and cars, but fewer trucks than cars. If all of the vehicles in the traffic jam were average mid-size sedans, and there was no gap between them, there would be approximately $\frac \approx 3,900$ trucks. For example: According to, the average mid-size sedan is about $13.5$ ft long and the average large pick-up truck is about $16.4$ ft long. Students should be given wide latitude on how they determine this length as long as they explain their thinking clearly and the estimates are reasonable, from cited references. The solution depends upon the estimate of the length occupied by a vehicle in the traffic jam. Teachers may have to help students who start on this (reasonable, but difficult) path make enough simplifying assumptions to reduce it to a solvable interpretation. For a limitation of the model, students might correctly note that the length of a traffic jam is not a constant, but rather a function of times that increases and decreases based on many complicated factors. Teachers can decide whether to make these conditions explicit to students, or just note that students who adopt different conventions may have answers that are, e.g., larger by a factor of 2 or 4. The problem is also ambiguous as to whether the traffic jam affects both direction of traffic, or just one (as assumed in the solution). For example, students may not know the standard convention that a "two lane freeway" has two lanes total, as opposed to two lanes in each direction. Given the uncertainties in assumptions, it does not make sense to report the number of vehicles to any greater accuracy than 100s.įinally, teachers should be conscious of possible interpretations of the problem, and limitations of the model. The task also provides students the opportunity to attend to the appropriate level of accuracy when reporting quantities (N-Q.3). In addition to giving practice with working with units (N-Q.1), the task gives students an opportunity to engage with N-Q.2 by working with a new unit appropriate to the question, namely the notion of the length occupied by a vehicle in a traffic jam, which consists of its length plus the gap to the next vehicle. Teachers can encourage students to compare their solutions with other students. This task, while involving relatively simple arithmetic, codes to all three standards in this cluster, and also offers students a good opportunity to practice modeling (MP4), since they must attempt to make reasonable assumptions about the average length of vehicles in the traffic jam and the space between vehicles.
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