Question

What is the fundamental difference in the calculation sequence of the los on merge/diverge sections versus weaving sections?

Answer 1

Answer:

In most of the existing highway capacity manuals, level of service (LOS) of freeway weaving segments and ramp junctions is

traditionally defined by the speed, volume or density in critical areas of merge, diverge and weaving manoeuvres. In that

traditional concept several capacity values of different critical areas (merge, diverge, weaving) as well as upstream and

downstream basic freeway segments within the influence areas are evaluated separately. In this paper, a new model which

considers the total segment of freeway merge, diverge, and weaving as an entire object is introduced. A combined volume-tocapacity ratio is used for defining the LOS of the total segment. According to the probability and queuing theory, the volume-tocapacity ratio of the whole segment can be considered as a combination of volume-to-capacity ratios in the different critical areas

under consideration. The parameters of the new model can be calibrated with field data. Those parameters are functions of the

number of lanes on the freeways, the number of lanes in the on-ramps or off-ramps, the length of the acceleration, deceleration,

or weaving sections. Varying the model parameters the function can be fitted to the existing capacity models for different types

of weaving segments or ramp junctions. With this model, the traffic quality (LOS) can be obtained directly as a function of the

volumes on the freeway and on the on-ramp or off-ramp respectively. The new model has the following advantages: a) a uniform

function for all types of freeway weaving segments and ramp junctions, b) traffic quality assessment for all critical areas under

investigation in one step, and c) easy calibration. The new model will be incorporated into the new edition of the German

Highway Capacity Manual

Step-by-step explanation: