A 2+1 median barrier road has a continuous three-lane cross section with alternating passing lanes. A central barrier provides road users protection from head-on and run-off-road crashes, and the overtaking opportunities improve efficiency and mean the road can cater for up to AADT of 20,000 (Bergh et al. 2016) or 25,000 (NCHRP 2003 referencing the German experience).
Motorcyclists are protected too. A Swedish study (VTI 2009) found that 2+1 roads with Wire Rope Safety Barriers reduced the risk of death and serious injury to motorcyclists by 65-70% (40-50% after sensitivity analysis)