Arrangement of streets in subdivisions

In the city of Mississauga, Ontario, queen of sprawl, there are a large number of subdivisions which have been built so that parts of their interior roads run parallel to the bounding arterial roads, with only a fence and a sidewalk between them. The houses inside the roads face the arterial roads. When you leave their front doors, you go down the sidewalk, cross the interior road, cross grass, climb the fence, cross more grass and a sidewalk, and walk out into the arterial road (where you get run over by an SUV.)

Here’s an example, from Google Maps. Note how parts of Constellation Drive and Applecroft Circle are right next to and parallel with Mavis Road.

Why the heck do developers do this? Wouldn’t it be more cost-effective to have a smaller set of roads further from the exterior of the property, and put in another row of salable houses with their backs to the arterial roads? It’s not like they don’t do that already right nearby.

This has been annoying me for a while. Thank you.

It took me about three readings to figure out exactly what you meant. That’s no reflection on you, it’s just kind of an abstract thing on the face of it. However, following Mavis Rd southeast a ways, I see the houses at the corner of Mavis and Rathburn are what you expect them to be like.

My only guess, and this applies just to this circumstance, is that Mavis is three lanes where “my” houses are and two lanes where “your” houses are. Perhaps they needed to leave extra room for a potential expansion of Mavis Rd to three lanes both way? If the backyards came up to the fence and they put in an extra lane, that leaves a lot more potential for a car in your swimming pool.

Just a WAG until a city planning expert comes along.

I don’t know about Ontario, but what I know about 'round here:

Different areas of town have different ‘allowable minimum’ lot sizes. The optimum layout (for the developer), of course, is to maximixe the number of lots while minimizing the amount of streets. (as you mention, Sunspace, having both sides of the streets in lots is preferable). Each lot must also be ‘buildable’; that is, the minimum square foot house (for the zoning) must fit on the lot while also adhering to minimum allowable setbacks. The actual laying out of the lots then becomes tricky, as you can’t have any lots which are too oddly shaped, or they will not meet the ‘setback’ requirements. There are also restrictions on the length of cul-de-sac streets (here they can be no longer than 600 feet IIRC); that restriction can cause you to ‘loop’ your street. Add in zoning requirements such as landscape buffers and you can see why sometimes you will end up with a ‘one-sided’ street.

There doesn’t seem to be room for another row of houses, leaving the developer (and city planners) with the following choices:

  1. Have numerous driveways/access points directly onto the arterial street (bad idea for safety and traffic flow reasons);

  2. Put the residential street on the other side of the houses (in other words, one lot away from the arterial street), which means the rear property line of houses is the arterial right of way, and the houses are 30-40 feet closer to traffic noise;

  3. Do it the way they did.

If you put Constellation on the other side of the first row of houses they would be closer to Mavis, and therefore exposed to more noise.

I thought about that, but it didn’t stop them in a lot of other places. Like Winston Churchill Boulevard, for instance. But it occurs to me that the houses that back onto the arterial roads are all older than the ones that don’t. I wonder whether zoning requirements changed during the 1990s?

Different size / shape plot of land. Looking at this one, there is no easy way to put the road along the perimeter of the lots like the first example. To do so would either cut into the number of lots, or their size, and require a lot more paving (that I assume the developer pays for)

Very possible. But in the example you cite, the extra road parallel to the artery would be either be superfluous (if you left the existing residential streets there), or create an access problem for the next row of houses in (if you deleted the existing residential roads for houses that currently back onto the artery).

You’ll notice that many of the houses in the row closest to the artery have very deep lots to creat a noise barrier. With landscaping, that is better than a road as a noise buffer, and otherwise more desireable, assuming that the extra road isn’t needed for access.

Laying out subdivisions to maximize buildable lots and also stay within the law is a science. Depending on the size and configuation of the large tract on which the subdivision is to be built, the best way to do it may lead to the parallel street issue you identified in the OP, or the alternate configuration that you just showed us.

It takes a good bit of talent as well; some people are just better at fitting lots and streets into a particular tract than others. There are many factors to be considered in the process, as I mentioned above.

In addition to the noise and space answers, I don’t think everyone would agree whether it is better to have the front or back yard exposed to the main artery. I suspect the layout of the house would particularly influence this trade-off. I think everyone would agree that having a road between your yard and the main artery is better than having your yard next to the main artery.

Where would the kids play street hockey? On the main artery? You monster.

It’s usually a good idea to have a subdivision that doesn’t become a shortcut to anywhere. Nobody goes down those streets unless they’re going to one of those houses. So, there’s not much traffic, and every driver you do see is your neighbor. I like that kind of neighborhood.

That seems like a lot of work.
Basically the short answer is they try and come up with a street pattern that maximizes the number of units.

This looks like the standard modern suburban subdivision design:
A block of divided highways approximately 1 mile on each side.
Each “block” bisected in each direction by a 4 lane avenue
Within each quadrant is an irregular pattern of feeder roads, drives and cul-de-sacs where the actual houses are.

It’s pretty common in newer cities where the terrain tends to be flatter.
Here’s some more examples outside of Dallas TX.