Determination of Fairway Width Requirements in the Free-Flowing Rhine
How much space do inland vessels need when navigating the Rhine? This is the question studied in the project on the determination of fairway width requirements in the free-flowing Rhine. The required fairway width is determined based on observations and ship dynamics analyses of actual traffic and compared with existing fairway widths between the Iffezheim barrage and the Dutch–German border. In addition to identifying and evaluating existing navigation bottlenecks, the results may also be used for other research questions in connection with the future development and possible measures required for the Rhine as an inland waterway.
The information sources used for determining fairway width requirements are on the one hand transport statistics, including information on the vessel types that travel, pass and overtake each other on the Rhine, and on the other hand precise measurements, which help to define traffic lane widths as a function of vessel dimensions, direction of travel and hydraulic flow conditions. Transport statistics data are derived from the signals recorded by the automatic identification system (AIS). Fleet structure and also time intervals between ships travelling on characteristic reaches of the Rhine can be derived, among others, from the frequency of individual vessel types counted at virtual cross-sections. AIS data on head-on encounters and overtaking manoeuvres are directly available as such; in addition, they can be used to determine statistical frequencies of ship interactions on all, i.e. also unmonitored, reaches. These frequencies are instrumental in evaluating the required widths for such interactions and in identifying any differences to existing fairway widths. The width requirement comprises the lane width required by the vessels involved, safety distances between the vessels and extra widths to account for wind and currents resulting from sailing close to the bank (Fig. 1).