**7.2 Passing sight distance (PSD)**

It represents enough free distance of traffic so that the driver can see the driver in front of him to be able to complete the process of circumventing without touching the car that passes without being intercepted by any counter vehicle may appear after the start of the bypass and then return to the right warm easily after the overtaking process. PSD is designed for two-lane highway as in **Table 5** which illustrate passing sight distance with respect to the design speed for passed and passing vehicle [16].
