2+1-roads Recent Swedish Capacity and Level-of-Service Experience

Abstract

The first Swedish 2+1 median barrier road was opened in 1998. The concept was to retrofit the standard existing two-lane 13 m paved width cross-section at 90 and 110 kph posted speed limit without widening. This design has one continuous lane in each direction, a middle lane changing direction every one to three kilometres with a median barrier separating the two traffic directions. Today over 2 700 km 2+1 median barrier roads are opened for traffic. AADTs vary from some 3 000 to 20 000 with an average just below 10 000 nowadays normally with 100 kph. The concept has lately been enhanced also to cover the existing 9 m paved width cross-section. The design concept is the same from a drivers viewpoint, one continuous lane in each direction with a middle lane changing direction and a separating median barrier. This is created by introducing a continuous median barrier and adding overtaking lanes within an overtaking strategy. The differences are the existence of 1+1-sections, less overtaking opportunities and a slightly more narrow cross-section. Some 15 projects are opened. The purpose of this paper is to summarize present knowledge on level-of-service issues as they are presented in Swedish design and assessment guidelines and to give an overview of field measurements and theoretical analytical and simulation studies supporting the recommendations

Assessment of Landscape Conflicts in Motorway Planning, NE Hungary

“…Due to the rise of speed limit and increase of traffic, the geometry of the road must be adapted to strict technical standards in order to ensure road safety (Gulyas, 2006;Aarts and Schagen, 2006) resulting in a greater intervention in the landscape: e.g. a 13 m wide two-lane road is less safe than a 16 m wide road (2+1 lanes) with a road separation cable barrier in the case of huge traffic load (Bergh et al, 2016). Moreover, in the case of a motorway the crown width is much wider (even 26.6 m as in the case of the M30 Motorway) and road safety depends e.g.…”

“…Moreover, in the case of a motorway the crown width is much wider (even 26.6 m as in the case of the M30 Motorway) and road safety depends e.g. on the width of the emergency lanes or the central median barrier (Bergh et al, 2016;Bramaister, 1999) making the motorway wider. So the environmental impacts of road development can be more significant because of the greater intervention in the landscape than they were before the construction of motorways.…”

Operation of 2+1 Road with High Shares of Heavy Vehicles

“…The impact of additional passing lanes on the quality of traffic flow is described in literature, from around Europe [2], [4], [7], [8], the USA [1], [3], [5], [12], and also other countries [9], [10], [11].…”

2 + 1 Highways: Overview and Future Directions

“…2 + 1 highways are used to provide high-performance rural highways as intermediate solution between common twolane highways and freeways [1,2] or as a safety countermeasure for two-lane highways [3,4]. In two-lane highways, faster vehicles that want to travel at their desired speed face the on-coming traffic in the opposite lane and may suffer delays because of their inability to pass slow-moving vehicles.…”