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 |
4 |
5 |
5 |
3 |
|
Roadway geometry |
Intersection design speed |
25 |
25 |
25 |
50 |
|
Traffic operations |
Operational performance intersection Opening day: 2022 Future demand: 2040 |
4 |
4 |
4 |
2 |
|
Construction impacts |
Driveways/Farms and other access points impacted |
12 |
11 |
9 |
13 |
|
Complexity of Construction and Schedule |
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 |
|
Notes:
- Transportation Research Board. 2010. NCHRP Report 672 Roundabouts: An Informational Guide, Second Edition.
- Growth is based on traffic volumes that were seasonally adjusted with a 'commuter' trend factor.
- Driveways / Farm and other access points currently within project limits.
- Ranking of costs includes assumptions of right‐of‐way acquisition, environmental mitigation, construction cost and scheduling.
- Estimated area of additional Right‐of‐Way and Temporary Easement needed for each alternative.
- Affected area includes construction in or around ditches and wetlands.
- Estimated area of total impervious surface with new construction.
- Operational performance based on the average queuing length and average vehicle delay.