City of Frisco Engineering Standards

Engineering Standards
B. Corner Visibility Triangles
1. The corner visibility triangle is defined at an intersection of two thoroughfares by extending
the two ROW lines from their point of intersection to a distance as shown on Table 2.12.
These two points are then connected with an imaginary line to form the corner visibility
triangle as shown in Figure 2.28. This corner visibility triangle shall be dedicated as ROW.
Type of
Thoroughfare
On
TABLE 2.12: Corner Visibility Triangle Distances
Type of Thoroughfare
At
Distance (1)
(X)
A, B, C
A, B, C, D, or any residential street that
potentially will be signalized
40’
A, B, C E, F, G that will remain unsignalized 25’
D, E, F, G D, E, F, G 10’
TxDOT Road,
Frontage Road
Use the specifications for a
Type A Thoroughfare
Unimproved
Road
D, E, F, G 30’
1. The corner visibility triangle shall have the same dimension on all corners of the intersection.
X
X
X
X
Corner Visibility Triangle
FIGURE 2.28: Corner Visibility Triangle for an Intersection
2. Vision at all intersections of thoroughfares shall be clear at elevations between thirty inches
(30”) and nine feet (9’) above the average gutter elevation within the corner visibility triangle
and meet AASHTO’s current minimum requirements.
3. Where alleys intersect residential Type E, F, and G thoroughfares, the corner visibility
triangle is measured as fifteen feet (15’) along the residential street ROW and five feet (5’)
along the alley ROW from the point of intersection. These two points are then connected
with an imaginary line to form the corner visibility triangle as shown in Figure 2.29. The
alley corner visibility triangle shall be dedicated as ROW.
Section 2 – Thoroughfare Design Requirements May 2012 Page 2-47