1. If you check in to a hotel on Friday and you see that the hallways have automatic lights. That is, when you step into the hall the lights go on. You can see without these lights, as there are other smaller lights that stay on, but the big lights only go on when you walk down the hall, is it permitted to leave the room on Shabbat?
2. Assuming it is permitted to leave the room, is this only because it is a sha’at ha-dechak, or can you even make a reservation at this hotel knowing ahead of time the situation with the lights?
To answer the second question first, one should definitely not make a reservation in this kind of hotel, and thereby get oneself into a difficult halachic quandry. It is important to check hotels for this issue before checking in, and to ensure that one won’t run into this problem.
Post factum, if one finds oneself in this tricky situation, there are a number of factors that can mitigate the severity of the problem.
If there is sufficient light to see comfortably without the extra lighting, it follows that activating the lights will be a “pesik reisha de-lo ichpat lei.” The result of having the lights go on is not “desirable.” Although we rule that this remains forbidden (see Shulchan Aruch 320:18, and Magen Avraham 20), it mitigates the severity of the action.
Another cause for mitigating the severity is the fact that the new types of fluorescent bulbs in common use today do not involve an actual “fire,” and therefore activating them might not involve a Torah prohibition.
In addition to the above, one can also walk backwards. According to many opinions, this will be sufficient in rendering the action of activating the lights a shinui, and therefore only a rabbinic prohibition — meaning that the case will be a pesik reisha for a rabbinic prohibition.
Under the circumstances, leaving the room will certainly be a mitzvah (prayer, Shabbos meals), and therefore there will apparently be some room for leniency. However, if possible, one should try to crawl under the sensors, therefore avoiding the issue.
The best solution to the problem is to ask a non-Jew to accompany you. This will be a pesik reisha by means of a non-Jew, which the Mishnah Berurah rules is permitted.
After saying all this, I must repeat that one should certainly be careful to avoid the problem by ensuring in advance that the hotel does not have such light-activating sensors.