A woman boarding a vehicle alone without a male relative
The verdict from juristic texts and principles is that it is not permissible for a woman to ride or board a vehicle alone with a foreign driver. However, what seems to me in this contemporary situation is different with regards to taxis shuttling within the cities. It is now a case of necessity that left no alternative for women as far as the transportation system is concerned. Therefore, it is not forbidden to board with a foreigner alone.
As for outside the city, it is not permissible to ride alone unless there are other passengers with them.
If a mahram or husband is waiting at the place of arrival, it is not forbidden for a woman to travel alone without the Mahram or husband by flight as this is also a necessity. Also traveling by plane cannot be compared with car. Like the plane, the train is also a means of transportation for a larger group of people under the system. The supervision of the officials travelling with them also clears any fears or doubt . The woman can travel with the mentioned means alone as long as there is someone to receive her on arrival.