Definition of a suitable design volume for highway capacity analysis
Since 2001, Germany has been using the traffic volume in 30th hour of the traffic demand duration curve as design volume. European road traffic statistics, however, apply the traffic volume in the 50th hour. At the order of the Federal Highway Research Institute (BASt) an appropriate hour (nth hour) should be established and alternative processes verified. The acquired recommendations were considered in the HBS (Manual for the Design of Road Traffic Installations) 2015.
Applying the traffic demand in the nth hour was found to be a useful basis for highway design. The choice of the design hour has relatively small influence on the analysis results, particularly if the 30th and 50th hour are compared. However, major advantages for a specific design hour could not be found in the investigation results. Regarding a harmonization of the European design standards, replacing the 30th by the 50th hour should be considered.