You may have seen a Site Plan that sectioned off a small area and labeled it "Site Triangle."

That's a great idea, but many argue it's spelled wrong.

It's understandable because the area is usually triangular and located on a "site."

But in this case, the dedicated area is all about vision.

A "Sight Triangle" is an area at an intersection or driveway entrance that should remain clear of visual obstructions so drivers can see oncoming traffic and pedestrians and vice versa.

The area might also be labeled as a "Visibility Triangle" or "Clear Vision Area."

Here's an example of obstructed visibility coming out of a private drive and at the street corner.

Typically, most local zoning ordinances do not require a Sight Triangle for one- and two-family dwellings.

Neither does the building code, so it's not an item on the AIBD CD Checklist. For now.

Yes, the landscaping looks beautiful. And homeowners deserve to have privacy.

In a small town that has seen its share of accidents, you may uncover a requirement as an unexpected surprise—like an "Easter Egg"—when you diligently review the zoning code.

So, here's one way a private property owner or a city might resolve the issue and provide for safe roadway travel.

It's called a Jumbo Convex Safety Mirror, and its price ranges between $350 and $500, depending on size, which varies from 13 inches to 48 inches in diameter.

Here is an affordable alternative:

When creating the Site Plan, designate an area, hatch it, and label it as a 10' x 25' (size should depend on the roadway) Sight Triangle (or Clear Sight Triangle, Clear Vision Area, etc.).

Then, include a note describing the triangle's purpose and restrictions. Such as, "Any fence, Hedge, or other object which will cause a sight visibility obstruction between 30" and 96" inches above grade must be located outside of this designated triangular area."

Other examples you might find in local ordinances could be as high as 36 inches and 10 feet above grade.

The key is to establish an unobstructed area for people sitting in a vehicle, riding a bike, or walking to view potential danger in every direction. An area above ground cover and below the lower branches of a tree.

Here are two examples.

If the building site is located on a corner or an intersection, a larger Site Triangle, such as 25' x 25', might be considered depending on the speed limit of the roadways and if there's a stop sign.

The triangle size for a driveway should also consider whether the homeowners will likely be backing out or leaving the property facing forward.

Here is a wonderful illustration shared by Durango, Colorado (left). Another on the right gives us an idea of how to depict the area on a construction drawing.

While not a requirement in most cases, clearly depicting sight triangles on construction plans is a best practice that building designers should prioritize.

By doing so, you help ensure that all project stakeholders are aware of the safety requirements for maintaining clear visibility, particularly at driveways.

This ultimately prevents obstructions that could jeopardize a child or pet that runs into the street unexpectedly or the student driver pulling out for the first time, among others.

Ensuring safety and visibility,
The A-Team

PS - If you'd like to view some examples of "official" zoning regulations relating to sight triangles on residential sites, St Petersburg, FL, has prepared a two-page PDF document instructing designers in their area, and the ordinance enforced by Weston, FL, is available online.