In the continuing search for examining possibilities for increasing the capacity of existing road infrastructure, air quality and all environmentally-related issues are playing an ever increasing important role in the decision making process. In addition in order to meet the agreed European standards for air quality on various sections of the existing highway network, it will be necessary to introduce additional measures to decrease air pollution. One of the possible measures to achieve this is to reduce the maximum speed on (selected sections of) the motorway road network to 80 km/u.Under contract to the Ministry of Transport, the AVV, research has been undertaken to assess the effects of reducing the maximum speed to 80 km/u on the ring roads of the four main cities of The Netherlands: Amsterdam, Rotterdam, Dem Haag and Utrecht. In theory a reduction of the maximum speed should make it possible to create an extra ('compact') lane on the existing highway and as such create extra capacity. The research project: "Reducing maximum speed and compact driving on reduced land-width (project working name: C80) has examined each measure individually and combinations of both of the measures. The scenarios tested differ only in the chosen lower maximum speed combined with an extra 'compact' lane on all sections of the ring roads of the four cities. In addition scenarios have been tested looking at an extra 'compact' lane on selected sections of the network, selected highway sections with a lower maximum speed and different maximum speeds during the peak periods and the rest of the day. The theme of one of an associated study is to investigate to what extent the modelled C80 measures have had on journey time reliability and accessibility. The New RegionalModel (NRM) for the Randstad has been used to model the various scenarios. Criteria used to measure the effects of the various scenarios include total number of vehicles, total vehicle hours, levels of congestion and average speeds. The analysis has been carried out at a relatively abstract level: all of the effects have analyzed at a city-wide level. Distinction hasbeen made between motorway and non motorway link types.Initial results demonstrate, when looking at geographical region of the Randstad as a whole,that accessibility in the peak periods improves as a result of a reduction of the maximum speed to 80 km/u in combination with an additional 'compact' lane. The reduction of the maximum speed during the off-peak period has a significant impact, owing to the lower levels of congestion, and results in a reduction in the average speeds on the motorway network and as such an decrease in accessibility. All in all this results in the fact that for an average working day all of the journey time savings that have been realized through extra capacity are cancelled out by the journey time losses as a direct result of the reduced maximum speed in the off-peak period. For the covering abstract see ITRD E135582.
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