Abstract: To minimize the impact of long-term following on safety and operational efficiency in long (extralong) tunnels and tunnel groups on mountain expressway, and to improve travelling comfort and experience, the authors conduct statistical analysis on number of highway tunnels and the distribution of typical tunnel lane changing schemes in Yunnan province, China. Then, investigations and analyses are conducted on the Laoying extralong tunnel of the Baoshan-Lushui expressway, the Huajiaoqing extralong tunnel of the DaliRuili expressway, and the Jiudingshan extralong tunnel of the ChuxiongDali expressway. Based on traffic flow, linear indicator, accident distribution, and driving needs, the minimum length of variable lanes in tunnels, the white solid line length of prohibited lane changes at tunnel entrances and exits, and the layout of variable lane sections in tunnel group sections are examined using real vehicle driving test and driving simulation. The conditions for allowing lane changes within the tunnel are as follows: (1) The white dashed lines should be set between the lanes of extralong tunnels to allow lane changes, white dashed lines can be set between the lanes of long tunnels to allow lane changes, white solid lines should be set between the lanes of the middle tunnel to prohibit lane changes, white solid lines must be set between short tunnel lanes to prohibit lane changes, and spiral tunnels should be equipped with white solid lines to prohibit lane changes. (2) The length of the white dashed line in tunnel must not be less than 249 m and should not be less than 399 m, and when the distance between two tunnels is no less than 400 m, white dashed line can be set between the tunnels to allow lane changes.

Key words: long (extralong) tunnels, tunnel groups, real vehicle driving, driving simulation, minimum length of variable lanes, prohibited lane change length