Intersection Design: Unacceptable Congestion

1839 Words8 Pages

LITERATURE REVIEW Congestion is the travel time or delay in excess of that normally incurred under light or free flow traffic condition. Unacceptable congestion is travel time or delay in excess of agreed upon norm which may vary by type of transport facility, travel mode, geographical location, and time of the day. (Patil, 2015) Traffic signals are one of the most effective and flexible active control of traffic and is widely used in several cities world-wide. The conflicts arising from movements of traffic in different directions is addressed by time sharing principle. The advantages of traffic signal includes an orderly movement of traffic, an increased capacity of the intersection and requires only simple geometric design. However, the …show more content…

Design elements that are particularly relevant include the number of lanes provided on each approach and for each movement, whether there are shared thru-and-turn lanes, the length of turn bays, the turning radii (especially important for pedestrians), the presence of additional through lanes in the vicinity of the intersection, the size and location of detectors, and presence or absence of left-turn phasing. Other geometric features, like additional through or turn lanes, can also have a significant positive impact on intersection capacity, provided that they are sufficiently long. The other aspect of intersection design is the perception and reaction of the end users. Various decisions need to be made as a user approaches the intersection, which makes it important to simplify the decision making process. Another aspect of the design is detection. Detectors provide the ability to sense vehicle and pedestrian demands at an intersection; enabling modes of operation that may be more efficient than fixed or pre-timed control. It is critical that functional and properly designed detectors communicate with the controller to ensure continued functional signal control at the intersection. Detectors that are improperly located or are an inappropriate length can unnecessarily extend the green indication and increase the frequency of phase termination to the maximum limit (i.e., max out). Conversely, a poorly located detector could cause premature gap-out. A protected left-turn phase provides a time separation for left-turning and opposing traffic streams and may reduce left turn delays or related crashes. However, the additional phase increases the minimum cycle length and may increase intersection delays and, in the case of a protected-only left-turn, may even increase left-turn delay. The topics discussed in this section are intended to serve as a

More about Intersection Design: Unacceptable Congestion

Open Document