Different communities have different rules when it comes down to residential streets, all dependent on so many factors that there is a lack of uniformity. That, however, doesn't mean that there shouldn’t be an ideal standard for residential streets now and into the future. When it comes to residential streets, there are several factors that come into play, things such as the speed of the vehicles along with safety of the pedestrians, parking on the street or not, and sidewalks, to mention some of the largest issues. Another very important factor, is the fact that land costs money, so from a development standpoint, if one can develop residential streets that are, for instance, 32 feet across, rather than 36 feet across, the developer of the residential community will be able to be more efficient in the usage of that land, and in all likelihood, be able to pass along to its consumers the cost savings, thereof, so that the width of streets most definitely has a cost factor involved.
When it comes to residential streets, at a minimum those streets must be able to allow traffic to flow in both directions, as one-way streets in residential sections is simply too restrictive and undesirable. Additionally, there must be a discussion as to on-the-street parking, to wit, allowing cars to park on either side of the street is most desirable, since it favors neither side, and also depending on the location of the residence, it may be necessary to mandate parking permits in the neighbor so as to cut down on unsolicited visitors from using residential streets as their preferred free parking location, for work, for school, or whatever, as well as encouraging the residents themselves to park their vehicles in either their garage and/or driveway so as to leave the street essentially free to true residential visitors, only.
Additionally, with very few exceptions, there should be sidewalks within a neighborhood, because without sidewalks, those walking, running, walking their dogs or whatever, will be walking out into the street, and/or possibly trespassing on a neighbor's lawn. In order to use space efficiently, though, only one side of the street needs to have a sidewalk, as one sidewalk should be sufficient to accommodate pedestrians. Also, to cut down on the speed of vehicles for the protection of pedestrians, some neighborhoods like to use speed humps, which ideally should never be used on flat surfaces but only in cases in which the road is sloping downwards in order to slow down the vehicle as necessary.
An ideal residential street would be one with one sidewalk, parking on both sides of the street, and wide enough that two cars can easily pass each other on the street when there are no vehicles parked on the street, but, however, when there is a car parked on the street, one car must yield the right of way to the other. Today, with the cost of land so high, there isn't a need or justification for two sidewalks, nor for a street to be so wide so as to easily accommodate traffic flow in either direction, even with cars parked on either side of the street. The fact of the matter is a narrower street will for the most part allow residents to be about their business without any noticeable downside, yet still providing all the desirable things that a good residential street should have, all with the understanding, that for the vast majority of the time, there won't be any undue inconvenience.