APPENDIX #8
OTHER CONCEPTS FOR THE AIRPORT ROTARY
Hyannis Access Study
Skewed Intersection
In this alternative, the Airport Rotary is eliminated and four approches are realigned to create a skewed four legged intersection. Route 132 and Route 28 East are aligned as the main through movement, whereas Route 28 West and Barnstable Road intersect at a skew. This alternative requires double left turn lanes at all approaches. This alternative was eliminated because of its awkward geometry, creating some difficult movements and projected traffic operations when compared to other at-grade intersection alternatives.
Appendix 8 Hyannis Access Study
28 to 28 Underpass with Intersection
This alternative provides a grade-separated bypass for the Route 28 to Route 28 movement with an at-grade four-leg signalized intersection. At-grade bypass lanes are provided for all right turn movements with the exception of the westbound Route 28 to Route 132 movement. The main issue with this alternative (and the other grade-separated intersection concepts) was several access limitations due to the grade-separation and the intersection at-grade. It was also determined that this alternative did not provide enough capacity or provide safe and efficient enough operation given the high construction and maintenance costs.
Appendix 8 Hyannis Access Study
132 to Barnstable Road Underpass with Roundabout
This alternative provides a grade-separated bypass for the Route 132 to Barnstable Road movement with an at-grade four-leg two-lane roundabout at the existing Airport Rotary intersection. At-grade bypass lanes are provided for all right turn movements. A tighter radius is utilized to reduce vehicle speeds entering the roundabout. The Task Force felt strongly that the property impacts, access limitations, and tunnel to downtown area were not reflective of their community interests.
Appendix 8 Hyannis Access Study
132 to Barnstable Road Underpass with Intersection
This alternative provides a grade-separated bypass for the Route 132 to Barnstable Road movement with an at-grade four leg signalized intersection. At-grade bypass lanes are provided for all right turn movements with the exception of the westbound Route 28 to Route 132 movement. The main issue with this alternative (and the other grade-separated intersection concepts) was several access limitations due to the grade-separation and the intersection at- grade. It was also determined that this alternative did not provide enough capacity or provide safe and efficient enough operation given the high construction and maintenance costs.
Appendix 8 Hyannis Access Study
Split Intersection (Compressed)
This alternative provides a split intersection at the airport rotary location. The roadways are realigned as two offset intersections with coordinated signals. Route 28 is the through movment while Barnstable Road and Route 132 are offset approximately 175 feet. Bypass lanes are provided for the Route 132 to Route 28 westbound and the Barnstable Road to Route 28 eastbound movements. All through movements are required to pass through both intersections with the exception of the Route 132 to Barnstable Road through movement. This alternative was eliminated because the close distance between the two intersections reduces vehicle storage and increases the likelihood of queue buildup impacting adjacent intersection operations.
Appendix 8 Hyannis Access Study
Split Intersection (Compressed) with Bypass Lane 1
This alternative was developed in an attempt to make the split intersection operate with a better level of service. An at-grade bypass lane was provided for the westbound Route 28 to Route 132 traffic. This alternative was rejected because it did not remove enough volume from the two intersections to provide adequate levels of service for all movements, nor did it solve the queue storage problem. It also introduced safety and access issues at the merge point on Route 132.
Appendix 8 Hyannis Access Study
Split Intersection (Compressed) with Bypass Lane 2
This alternative was developed in an attempt to make the split intersection operate with a better level of service. A signalized at-grade bypass lane was provided for the westbound Route 28 to Route 132 traffic. Additionally, the Barnstable Road to Route 132 movement is provided a through access to the bypass lane. This alternative was rejected because it did not remove enough volume from the two intersections to provide adequate levels of service for all movements, nor did it solve the queue storage problem. Also, the access to the westbound Route 132 bypass lane at the eastern intersection created safety concerns as there is no physical barrier to prohibit movements other than the intended movement.
Appendix 8 Hyannis Access Study
Split Intersection (Spread) with Bypass Lane
This alternative provides a widened split intersection at the airport rotary location. Route 28 is the through movment while Barnstable Road and Route 132 are offset approximately 400 feet. The roadways are realigned as two offset intersections with coordinated signals. Bypass lanes are provided for all right turns with the exception of the eastbound Route 28 to Barnstable Road movement. All through movements are required to pass through both intersections with the exception of the Route 132 to Barnstable Road through movement. This alternative was eliminated because the bypass lane was determined to provide minimal operational improvements while introducing additional safety concerns.
Appendix 8