Over the last twenty years, European countries have built several thousand kilometres of "2+1 roads", in which an existing or new 13 to 14 metre wide, paved two-lane road segment (8 to 20 kilometres long) is re-striped into three traffic lanes, with the centre lane used as the passing lane in alternate directions. The European 2+1 roads serve traffic volumes from 6,000 AADT to 30,000 AADT. Many are quasi-freeways with grade separated access. At-grade intersections are discouraged; where they cannot be avoided, they are, as a rule, placed in the transition zone between adjacent alternating passing lanes. From the European experience, it is evident that the 2+1 road design aids in the economic, environmental and social sustainability of roads, because it: (a) reduces fuel consumption by improving the road's Level of Service by reducing platooning and congestion; (b) helps defer or avoid the need for road twinning; and (c) reduces the rate of fatal and serious injury collisions by an average 25 percent. The European 2+1 road design has not yet been implemented in North America. The objective of the study reported in this paper was to assess the feasibility of implementing the European 2+1 road concept on the rural Alberta highway network managed by Alberta Transportation (AT), and if found feasible, to propose a small number of segments for implementation. For the covering abstract of this conference see ITRD number E217481.
Abstract