Gemara

(Rav Yehudah): One may not ruin a path that the public has been using.

11b (Rav Huna): If a member of a Mavuy wanted to close his opening to the Mavuy, the people of the Mavuy can stop him, for this would increase the amount they must walk.

Rebbi holds that people in a Chatzer open to a Mavuy may use the part of the Mavuy from their entrance and outwards, but they may not go inwards.

12a (Rabah bar bar Chanah): If a Mavuy is open to a road leading to another city, and people of this city want to close it, people of the other city can stop them, even if another path connects the cities, due to Rav Yehudah's law (one may not ruin a path that the public has been using).

(Rav Anan): If a Mavuy is open to the Reshus ha'Rabim, and people of the Mavuy want to put doors there, people of the city can stop them.

Assumption: This is forbidden only within four Amos of the Reshus ha'Rabim, due to R. Zeira's law that the four Amos adjacent to the Reshus ha'Rabim are like the Reshus ha'Rabim.

Rejection: No. R. Zeira discusses what is considered a Reshus ha'Rabim regarding Safek Tum'ah. Rav Anan's law is because sometimes the Reshus ha'Rabim is crowded and people enter the Mavuy, even past four Amos.

Rishonim

Rif and Rosh (5a and 1:23): A Tosefta (Bava Metzia 11:9) teaches that if one has an opening in a Mavuy, people of the Mavuy cannot force him to put doors at the entrance to the Mavuy. He can say 'I want to enter carrying my bundle until my house.'

Nimukei Yosef (4b DH Masnisin): Only people in a Chatzer can force each other to make a door. People in a Mavuy cannot force him, like the Tosefta says. It connotes that he can stop them.

Nimukei Yosef (7b): Rav Huna discusses a Mavuy open to a storage area or valley. If it were open to Reshus ha'Rabim, why did Rav Huna say that people of the Mavuy can stop him? Even people of Reshus ha'Rabim can stop him, like we say on 12a! There, we do not discuss a Mavuy open on both sides, for we say that sometimes people pass through. However, if there is a doorframe and pillars to stop the masses from passing through, they may set up doors even though it is open to Reshus ha'Rabim.

Nimukei Yosef (8a DH Garsinan): One may not ruin a path that the public has been using only if they initially were permitted to use it.

Rosh (44): The Halachah follows Rebbi. (Since people of a Chatzer have no rights further inside the Mavuy,) an inner Chatzer may close near its opening. Rav Anan taught that people of the city can stop them! He discusses a Mavuy open to Reshus ha'Rabim, and Rebbi discusses a Mavuy open to a Simta (shoulder of Reshus ha'Rabim) or Karmelis. I say that for this law, we do not distinguish Reshus ha'Rabim from Karmelis or a Simta, since many pass through. Rather, Rebbi discusses a Mavuy open to a Mavuy open to Reshus ha'Rabim.

Rivash (253): A case occurred in which a Beis ha'Keneses wanted to make seats for more people. One person complained that this will give him less room to get to his place. This is a valid claim, just like one in a Mavuy can stop them from erecting doors, for it will stop him from carrying a bundle to his house.

Rebuttal (Mas'as Binyamin 4): Claims of burden, toil and lack of room apply to a commoner's needs. For Avodas Hash-m in a Beis ha'Keneses, these are preferred. There is more reward for one who is cramped or must walk further! Surely one must bear inconvenience to allow the Beis ha'Keneses to make room for others. Sometimes one must even do a light Isur and forfeit money to save others from a great Isur, e.g. to free a half slave. For a Mitzvah of the Rabim (to enable more to pray in the Beis ha'Keneses), we force an individual even if there was negligence. Normally, a path must be four Amos wide. A path in a vineyard is not needed so much for usage, so two and a half Amos suffice. All the more so one does not need so much room in a Beis ha'Keneses! The Rivash said that the concern is not only for a bundle. I say that it is! One may not diminish a path of the Rabim. For an individual's path, we leave as much as he needs.

Rambam (Hilchos Shechenim 5:13): If one has an opening in the Mavuy, people of the Mavuy cannot force him to make a door for the Mavuy. He can say 'I want to enter carrying my bundle until my house.' If a Mavuy is Mefulash (open on both ends) to Reshus ha'Rabim, and the residents want to erect doors, people of Reshus ha'Rabim can stop them, for sometimes they (people in Reshus ha'Rabim) are crowded and enter the Mavuy.

Rambam (Hilchos Nizkei Mamon 13:24): If one recessed his property from Reshus ha'Rabim, he may extend a ledge at any time. He may never return the walls, for one may not ruin a path that the public has been using.

Ramban (11b DH Echad): The Gemara suggested that if a Mavuy is Mefulash to a Reshus ha'Rabim, and people of the Mavuy want to put doors there, people of the city can stop them only within four Amos of the Reshus ha'Rabim. The Ra'avad says that the Mavuy is open on only one side to Reshus ha'Rabim. If it were open on both sides, why would we think that past four Amos is different? Also, why did we answer that sometimes the Reshus ha'Rabim is crowded and people enter past four Amos? People constantly pass through! We find that a Mavuy closed on three sides is called Mefulash (Shabbos 117a). This is reasonable. However, all Chachmei Sefard says that it is Mefulash on two sides. If it is Mefulash on one side, it is only for people of the Mavuy. If it is Mefulash on two sides, it is open to Reshus ha'Rabim, and it is not for use (of people of the Mavuy). The Gemara did not say that people (of the city) pass through, for even when there is another path, they can stop them from making doors.

Poskim

Shulchan Aruch (CM 162:1): If people in a Mavuy want to put doors at the entrance to the Mavuy, even one of them can stop them and say 'I want to enter carrying my bundle until my house.' Even if they all agree, people of Reshus ha'Rabim can stop them.

SMA (2,3): The lintel above the door and the door itself would prevent one from carrying a bundle until his house without putting it down first, and this is burdensome. Due to this reason, people of the Mavuy can protest in any case, even if there is a lintel and pillars. The Rema below explains times when people of Reshus ha'Rabim cannot protest.

SMA (4): This is whether the Mavuy is open on one side or on two sides.

Rema: Even if they sold the Mavuy to one who intends to put doors on it, and they announced that anyone who does not protest will lose his rights, still they can protest.

Darchei Moshe (1): In Teshuvah 339, the Rashba says that even if they announced that anyone who does not protest will lose his rights, they did not lose their rights, for the opening of the Mavuy announces their rights, so they need not protest.

Shulchan Aruch (ibid): (They can stop them) even if they want to put the doors far inside the Mavuy, for sometimes Reshus ha'Rabim is crowded and people enter the Mavuy.

SMA (6): On market day it is crowded with people and animals from other cities and they cannot fit in Reshus ha'Rabim, so they enter the Mavo'os. The Tur says that the same applies if it is open to Karmelis or a Simta. This is why the Rema permits a Mavuy open to a Mavuy open to Reshus ha'Rabim or a Simta, i.e. but not a Mavuy open to a Simta.

Rema: However, if a small Mavuy is open to a Mavuy open to Reshus ha'Rabim or a Simta (a shoulder of Reshus ha'Rabim), people of the small Mavuy may make doors for it.

Gra (4): This is unlike the opinion in the Rosh that distinguishes a Simta for Reshus ha'Rabim.

Rema: Some say that even if it is open to the Reshus ha'Rabim and at the opening is noticeable like an opening with pillars, they can erect doors.

SMA (7): The Tur forbids only when the width of the Mavuy is totally open to Reshus ha'Rabim. If the opening in the fourth wall of the Mavuy is not as wide as the Mavuy, and there are pillars and a lintel to inhibit people of Reshus ha'Rabim from entering, one may erect doors.