Dua-When beginning the journey recite

اللَّهُمَّ إِنَّا نَسْأَلُكَ فِي سَفَرِنَا هَذَا الْبِرَّ وَالتَّقْوَى وَمِنَ الْعَمَلِ مَا تَرْضَى اللَّهُمَّ هَوِّنْ عَلَيْنَا سَفَرَنَا هَذَا وَاطْوِ لَنَا بُعْدَهُ اللَّهُمَّ أَنْتَ الصَّاحِبُ فِي السَّفَرِ وَالْخَلِيفَةُ فِي الْأَهْلِ اللَّهُمَّ إِنِّي أَعُوذُ بِكَ مِنْ وَعْثَاءِ السَّفَرِ وَكَآبَةِ الْمَنْظَرِ وَسُوءِ الْمُنْقَلَبِ فِي الْمَالِ وَالْأَهْلِ وَأَعُوذُ بِكَ مِنَ الْحُورِ بَعْدَ الْكُورِ وَدَعْوَةِ الْمَظْلُومِ
"O Allah, we seek goodness from You and piety from this journey and (the ability to do) good actions by which You are pleased. O Allah, ease this journey for us and make us transverse the road quickly. O Allah, You are our companion in this journey and deputy (guardian) over our household whom we left behind. O Allah, I seek refuge in You from the difficulties of the journey and from seeing bad things and from a bad return at home and household and from the dua of the oppressed".
Note: It is Mustahab to perform two rakaats Nafl Salaat before commencing a journey.

(Kitabul Askar-Li-Nawawi)