A woman can't do wudu in public,so what should she do in journey, is it permissible for her to do tayammum instead of wudu in such a situation?
Tayammum is not only valid during the absence of water. If one is ill or during any other instance where the use of water could affect the person negatively it is acceptable to make tayammum. If a woman feels restricted to either exposure or tayammum during travel she should do what is most logical to her and ask Allah for forgiveness, for in the end, only He is all-knowing. These protocols and procedures are set in place to provide Muslims with alternatives in times of need. We should use them justly and with good intentions, not out of idleness or convenience.
The Quran says: “Allah intends for you ease and does not intend for you hardship.” (Qur’an, 2:185)
Remember that excessive stringency of the rules does not necessarily equate to the level of piety.