ITE Journal - May 2020 - 48

Major street
Number
Low
through lanes AADT
2
0

4

High
AADT
7,500

Number
through
lanes:
Low AADT:

2
0

High AADT:
5,000
Safest
All-way stop

7,500 10,000

CMF
Safest

10,000 15,000

CMF
Safest

10,000 15,000

CMF
Safest

15,000 20,000

CMF
Safest

20,000 25,000

CMF
Safest

25,000 30,000

CMF
Safest

30,000 and
above

Table 2. Safest feasible intersection design (SaFID) based on all crashes.
Minor street

CMF
Safest

6

Any

CMF
Safest

8

Any

CMF
Safest
CMF

0.4
One-lane
roundabout
0.7
One-lane
roundabout
0.7
Unsignalized
RCI
0.7
Unsignalized
RCI
0.7
Unsignalized
RCI
0.7
Unsignalized
RCI
0.7
Unsignalized
RCI
0.7
Unsignalized
RCI
0.7
Unsignalized
RCI
0.7

4

6

8

25,000 and
above

Any

Any

n/a

n/a

n/a

5,000

7,500

10,000

10,000

15,000

20,000

7,500
All-way stop

10,000
n/a

15,000
n/a

15,000
n/a

20,000
n/a

25,000
n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

One-lane
roundabout*
0.7
Signalized RCI

n/a

n/a

n/a

n/a

n/a

n/a

Signalized RCI

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

n/a

0.4
One-lane
One-lane
roundabout
roundabout
0.7
0.7
One-lane
One-lane
roundabout
roundabout
0.7
0.7
Unsignalized Unsignalized
RCI
RCI
0.7
0.7
Unsignalized Signalized RCI
RCI
0.7
0.8
Signalized RCI Signalized RCI

0.8
Signalized RCI

0.8
Signalized RCI Signalized RCI

0.8
Signalized RCI

0.8
0.8
Signalized RCI Signalized RCI Signalized RCI

0.8
0.8
Signalized RCI Signalized RCI

0.8
Signalized RCI

0.8
0.8
Signalized RCI Signalized RCI

0.8
Signalized RCI

0.8
0.8
Signalized RCI Signalized RCI

0.8
Signalized RCI

0.8
0.8
Signalized RCI Signalized RCI

0.8
Signalized RCI

0.8
0.8
0.8
Signalized RCI Signalized RCI Signalized RCI Median un/a
n/a
turn
0.8
0.8
0.8
0.8
Signalized RCI Signalized RCI Signalized RCI Median un/a
n/a
turn
0.8
0.8
0.8
0.8
Signalized RCI Signalized RCI Signalized RCI Median u- Median un/a
turn
turn
0.8
0.8
0.8
0.8
0.8
Signalized RCI Signalized RCI Signalized RCI Median u- Median u- Median uturn
turn
turn
0.8
0.8
0.8
0.8
0.8
0.8

0.8

0.8

0.8

* One-lane roundabouts are generally feasible if the combined AADT is less than 25,000. If a one-lane roundabout is infeasible a signal is the safest feasible design.

Major street
Number
Low
through lanes AADT
2
0

4

High
AADT
7,500

Number
through
lanes:
Low AADT:

2
0

High AADT:
5,000
Safest
All-way stop

7,500 10,000

CMF
Safest

10,000 15,000

CMF
Safest

10,000 15,000

CMF
Safest

15,000 20,000

CMF
Safest

20,000 25,000

CMF
Safest

25,000 30,000

CMF
Safest

30,000 and
above

Table 3. Safest feasible intersection design (SaFID) based on injury crashes.
Minor street

CMF
Safest

6

Any

CMF
Safest

8

Any

CMF
Safest
CMF

4

5,000

7,500

10,000

10,000

15,000

20,000

7,500
All-way stop

10,000
n/a

15,000
n/a

15,000
n/a

20,000
n/a

25,000
n/a

n/a

n/a

n/a

n/a

0.4
0.4
One-lane
One-lane
One-lane
roundabout roundabout
roundabout
0.4
0.4
0.4
One-lane
One-lane
One-lane
roundabout roundabout
roundabout
0.4
0.4
0.4
Unsignalized Unsignalized Unsignalized
RCI
RCI
RCI
0.5
0.5
0.5
Unsignalized Unsignalized
Two-lane
RCI
RCI
roundabout
0.5
0.5
0.5
Unsignalized
Two-lane
Two-lane
RCI
roundabout
roundabout
0.5
0.5
0.5
Unsignalized
Two-lane
Two-lane
RCI
roundabout
roundabout
0.5
0.5
0.5
Unsignalized
Two-lane
Two-lane
RCI
roundabout** roundabout**
0.5
0.5
0.5
Unsignalized Median u- Median u-turn
RCI
turn
0.5
0.7
0.7
Unsignalized Median u- Median u-turn
RCI
turn
0.5
0.7
0.7

May 2020

i te j o urnal

8

25,000 and
above

Any

Any

n/a

n/a

n/a

n/a

n/a

n/a

One-lane
n/a
n/a
n/a
n/a
n/a
n/a
roundabout*
0.4
Two-lane
Two-lane
n/a
n/a
n/a
n/a
n/a
roundabout
roundabout
0.5
0.5
Two-lane
Two-lane
Two-lane
n/a
n/a
n/a
n/a
roundabout
roundabout roundabout
0.5
0.5
0.5
Two-lane
Two-lane
Two-lane
Two-lane
n/a
n/a
n/a
roundabout
roundabout roundabout roundabout**
0.5
0.5
0.5
0.5
Two-lane
Two-lane
Two-lane Median u-turn Median un/a
n/a
roundabout
roundabout roundabout**
turn
0.5
0.5
0.5
0.7
0.7
Two-lane
Two-lane
Median u- Median u-turn Median un/a
n/a
roundabout** roundabout**
turn
turn
0.5
0.5
0.7
0.7
0.7
Median u-turn
Median uMedian u- Median u-turn Median u- Median un/a
turn
turn
turn
turn
0.7
0.7
0.7
0.7
0.7
0.7
Median u-turn
Median uMedian u- Median u-turn Median u- Median u- Median uturn
turn
turn
turn
turn
0.7
0.7
0.7
0.7
0.7
0.7
0.7

* One-lane roundabouts are generally feasible if the combined AADT is less than 25,000. If a one-lane roundabout is infeasible a signal is the safest feasible design.
** Two-lane roundabouts are generally feasible if the combined AADT is less than 45,000. If a two-lane roundabout is infeasible a median u-turn is the safest feasible design.

48

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ITE Journal - May 2020

Table of Contents for the Digital Edition of ITE Journal - May 2020

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