Level of service
The traffic quality is a calculated quantity which is to be determined in the planning of roads. With the calculation of the traffic quality can be demonstrated that the new road can handle the expected traffic load with the required quality and the predetermined speed by RAS N is achieved. The detection of the traffic quality can be calculated only on two-lane highways outside of nodes and streets of the category group AI to A III.
- 2.1 assign input values for calculation
- 2.2 traffic intensity
- 2.3 Traffic density
- 3.1 Level of service quality ( Level of Service)
Input values
For the detection of traffic quality following input values are required:
Travel speed VB
This rate is an average for all cars, which is aimed at the new section of road. It is determined by the spatial and regional planning.
Design traffic volume qB
This size is the traffic demand ( including heavy traffic share FOSS) in the new section again. It can be determined from the traffic forecast. You can fall back on a traffic report (model forecast) or on an extrapolation ( trend forecasting ).
Lines of the track position and height
This information is needed to account for the slope and the curviness in detecting the traffic quality.
Dividing the road into equivalent sections
The road should be divided into equal sections. The classification depends on the pitch and the tortuosity in particular. The sections are not less than 300 m to select.
Calculation
Assign input values for calculation
The sections are allocated slope classes ( 1-5 ). Depending on the pitch the fictional rated vehicle reaches a different average speeds. In addition to the pitch class, the curviness and percentage of heavy traffic are calculated for each section. These variables have a significant influence on the quality.
Traffic intensity
From the values above the traffic volume can using tables, are determined within the sections. It has the unit vehicles per hour and applies to both lanes.
Traffic density
To determine the traffic quality is a ratio of traffic volume and medium-sized passenger car travel speed to form. From these notional traffic density, measured in vehicle per kilometer, the new road may be classified into levels of quality.
See also Main article traffic density
Result
Level of service quality ( Level of Service)
Depending on traffic, the road quality level A ( good quality traffic ) have to Level F ( bad traffic quality). Is the desired quality level of the design requirement is not reached, measures have become seized, to produce the required quality.
The definition of quality levels is, inter alia, in the manual for the design of road traffic facilities (HBS 2001, Research Institute for Road and Transportation Association, Cologne) published.