Conceptual Layout

The intersection of Lennon Road and Morrish Road was included in the early preliminary engineering phase with support from the Genesee County Road Commission due to intersection safety concerns. This intersection is included in the 153 intersections that passed the skim analysis for experiencing crashes correctable by a roundabout and is a secondary analysis Tier Two intersection.

During the skim analysis, it was observed that there were 11 angle crashes and 2 head on left turn crashes over the 5-year period. These crashes resulted in zero fatalities, three type A injuries, five type B injuries, and eight type C injuries at the intersection.

The intersection of Lennon Road and Morrish Road is a two-way stop control intersection. Stop signs are present on the Lennon Road approaches and overhead flashing beacons are present for all approaches. Lennon Road runs east/west and is a two-lane roadway with one lane in each direction. Morrish Road runs north/south and is a two-lane road with one lane in each direction. Adjacent to the intersection, all quadrants are currently vacant. An aerial of the existing intersection can be seen in the photo above.

An operational analysis of the no-build condition was completed for the intersection using the 2045 forecast traffic volumes. The results of the analysis for future no-build conditions reveals that all approaches operate at LOS C or better in the AM and PM peak hours, except for the westbound Lennon Road approach in the PM peak hour which is LOS D.
 
The 95th percentile queue lengths were reviewed at the intersection and results showed that the approaches experienced a maximum queue length of 65 feet (3 vehicles) during the AM peak hour and 79 feet (4 vehicles) during the PM peak hour.

The operational results for future no-build conditions are presented in the table below.

A single-lane roundabout with an inscribed circle diameter of 140 feet would provide excellent traffic operations and improve safety at this intersection. It is likely that a small amount of permanent right-of-way acquisition would be needed in all four of the intersection quadrants. Overhead power poles are located in three quadrants and would likely be impacted. A concept design exhibit for this intersection can be found in the slide above. If desired later in the design process, a compact roundabout with diameter of 120 feet or less could be considered at this location. A compact roundabout could result in lower right-of-way impacts and cost.

An operational analysis of the roundabout (build) condition was completed for the intersection using Rodel software and the 2045 forecast traffic volumes. The results of the analysis for roundabout (build) conditions reveal that all approaches and movements at the intersection operate at LOS A during the AM and PM peak hours.

The 95th percentile queue lengths were reviewed, and results showed that all approaches would experience a maximum queue length of 1.8 vehicles during the AM peak hour and PM peak hour for the single-lane roundabout design.

The operational results for future roundabout (build) conditions are shown in the table below.

A roundabout appears feasible at this location, assuming GCRC can acquire the limited right-of-way that may be needed.

An opinion of probable cost was developed for the single-lane roundabout. The probable cost is $1.41 million in year 2025 dollars. This cost includes a 20 percent contingency and 3 percent annual inflation.

Potential funding sources for this improvement could include regular road improvement funding, safety funds, or an earmark. A TOR was computed with a result of 5.41.

For a complete breakdown of the estimate please review the full report below.