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The project team evaluated four design alternatives for the Farmington and River roads intersection (including a traffic signal and three roundabout alternatives) using seven key criteria. The results of the alternatives analysis is below.

 

 

Evaluation Criteria
Single lane roundabout alternatives
Signalization

Centered on intersection

Off center

Southwest

Intersection

Safety

Intersection safety
1-5 (5 being the safest)

4

5

5

3

Roadway geometry

Intersection design speed

25

25

25

50

Traffic operations

Operational performance intersection
1-5 (5 being the safest)

Opening day: 2022 

Future demand: 2040

 


5

4

 


5

4

 


5

4

 


3

2

Construction impacts

Driveways/Farms and other access points impacted

12

11

9

13

Complexity of Construction and Schedule
1-5 ( 5 Being the Simplest)

1

2

4

2

Costs

Estimated Construction cost

$$$

$$

$$

$

Right-of-Way impacts

Right-of-way (acres)

1.4

1.4

2.1

1.4

Structure Impacts

2

2

2

2

Natural environment

Floodplain Impacted

No

Yes

Yes

No

Impervious Surface Area (ac)

2.7

3.2

3.4

4.3

 

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Notes:
  1. Transportation Research Board. 2010. NCHRP Report 672 Roundabouts: An Informational Guide, Second Edition.
  2. Growth is based on traffic volumes that were seasonally adjusted with a 'commuter' trend factor.
  3. Driveways / Farm and other access points currently within project limits.
  4. Ranking of costs includes assumptions of right‐of‐way acquisition, environmental mitigation, construction cost and scheduling.
  5. Estimated area of additional Right‐of‐Way and Temporary Easement needed for each alternative.
  6. Affected area includes construction in or around ditches and wetlands.
  7. Estimated area of total impervious surface with new construction.
  8. Operational performance based on the average queuing length and average vehicle delay.