Class II two-lane highway is a highway on which motorists do not necessarily expect to travel at relatively high speeds. The level of service (LOS) on a Class II two-lane highway is defined by one performance measure: percent time-spent-following (PTSF). The LOS threshold defined by PTSF for Class II facilities is shown in the following table:

LOS Criteria for Two-Lane Highways

  Class I Class II
LOS Percent Time- Spent-Following Average Travel Speed (mph) Percent Time-Spent-Following
A <35 >55 <40
B 35-50 51-55 41-55
C 51-65 46-50 56-70
D 66-80 41-45 71-85
E >80 <40 >85

Two-lane highways that function as access routes to Class I facilities, serve as scenic or recreational routes that are not p rimary arterials, or pass through rugged terrain generally are assigned to Class II. Class II facilities most often serve relatively short trips, the beginning and ending portions of longer trips, or trips for which sightseeing plays a significant role.