2+1차로 도입효과 및 적용방안 연구

A Study on Assessing Effect and Application of 2+1 Road

A 2+1 road has a three-lane cross section with alternating passing lanes. 2+1 roads can be attractive alternatives to two- or four-lane roads with traffic volumes, which don't satisfy design traffic volume for four-lane road but exceed the capacity of two-lane road. The objectives of this research are to assess the potential traffic operational characteristics and benefits and to develop traffic volumes required for the use of 2+1 roads. Based upon the simulation results of this research, 2+1 road can operate at level of service D or better for any average daily traffic volumes of 10,000 to 30,000 vehicles per day, which exceed the capacity of two-lane road, similarly to four-lane road. 2+1 roads could be introduced for many two-lane roads with about 20,000 vehicles per day among the roads to be enlarged to four-lane roads. It is noticed that the steeper the vertical grade of 2+1 road is, the larger the effect of 2+1 road is. Therefore 2+1 road expected to be much more effective than four-lane road because our country has many rolling or mountainous terrains and to be largely contributed to reduce the environmental destructions and budget constraints.