13th Street and Dayton Avenue – Ames, IA

Intersection StudyByungOck Kim

Greg Karssen

13th Street and Dayton Avenue - Location

13th Street and Dayton Avenue – Lane Configuration

13th STREETD A Y T O N

A V E

Approach #2

Approach # 4

Approach #3

13th Street and Dayton Avenue – Images

13th Street and Dayton Avenue – Images

Looking west

Looking south

Looking east

Looking north

13th Street and Dayton Avenue – Traffic Volumes

Intersection Approach Label in Figure 2 AADT Left turn Thru Right turn

East Approach 1 13900

North Approach 2 5933

West Approach 3 13900

South Approach 4 5933

13th Street and Dayton Avenue – Crash History

Table 1: Crash Frequency

Table 2: Crash Types

MAJOR CAUSES

(7) Failure to Yield ROW – Left Turn(4) Ran Traffic Signal(3) Following Too Close (Rear End)(2) Driving Too Fast for Conditions

**Signalized intersection crashes…

Crash Diagram• This diagram shows the

major injury crashes were angle collisions involving a turning vehicle and a vehicle proceeding through the intersection

13th Street and Dayton Avenue – Crash Countermeasures

Crash Pattern Probable Cause Data Needs Countermeasures already there?Left-turn collisions Large volume of left turns volume data provide left turn signal phase Yes

absence of left-turn phase signal timing info retime signal

No protectedturns onNorth/South

traffic conflictsexcessive speed on approaches speed study reduce speed limit on approaches n/a

Right-angle collisions excessive speed on approaches speed study reduce speed limit on approaches n/ainadequate signal timing signal timing info retime signallarge total intersection volumes volume data turn lanes yes

traffic conflictsRear End Colissions large number of turning vehicles volume data left turn lanes Yes

at signalized intersections traffic conflicts provide left turn signal phase Yesinadequate signal timing signal timing info retime signal

all red phase Yes

13th Street and Dayton Avenue – Recommendation #1

• Left turn Signal phase– Evaluate signal times

for left turns on EB/WB approaches

– Provide exclusive left turns for NB/SB approaches…special concern for trucks and sight problems

Looking north…imagine a truck here

13th Street and Dayton Avenue – Recommendation #2

• P-Turn, “quadrant intersections”– Unconventional turns– Two right turn

movements (through-right-right) replace single left turn movement

• Follow vehicle on street B as it moves to street A Source: FHWA

13th Street and Dayton Avenue – Recommendation #3

• Offset Left Turn Lanes

– Improves sight distance for left-turning vehicles

– The left turning vehicle can see around the opposing left turning vehicle

Questions??

??