Final answer:
In heavy city traffic, it's prudent to prepare for a turn one or two blocks in advance. Pedestrian safety when crossing the street depends on the distance of oncoming cars, their speed, and the pedestrian's walking pace. Traffic flow models can provide insights but may not fully capture the complexity of real-world conditions.
Step-by-step explanation:
In heavy city traffic, it is critical to plan maneuvers well in advance due to increased vehicle density and the potential for sudden stops and changes in traffic flow. A specific distance or number of blocks cannot be universally prescribed as it depends greatly on traffic conditions, the speed at which one is traveling, individual city layouts, and local driving norms. However, as a rule of thumb, preparing to change lanes or turn at least one or two blocks ahead is considered prudent. This allows for a smooth flow of traffic and a margin of safety for all road users.
Regarding crossing streets, safety is paramount. If a car is 28 meters away, equivalent to 8 car lengths, whether or not it is safe to cross depends on several factors such as the car's speed, the pedestrian's walking speed, and visibility conditions. In towns and cities with a speed limit of 60 km/h, crossing requires critical judgment. It is generally advised that pedestrians wait until cars are farther away to ensure enough time to cross safely, especially since cars can cover distances quickly at high speeds.
The importance of these traffic concepts extends to pedestrians, especially when considering how to safely navigate road crossings. The distance one can cross safely depends on both the pedestrian's speed and the speed of oncoming traffic. Meanwhile, building a city traffic flow model can help test hypotheses about traffic patterns and could suggest better urban planning strategies. Nevertheless, certain limitations like unpredictable human behavior and varying traffic conditions may not be fully accounted for in such models.