This item is sponsored by Commissioner Steven Meiner and was referred to the Neighborhood and Quality of Life Committee (NQLC) by the City Commission on June 24, 2020.

The intersection of West Avenue and Dade Boulevard is a four-leg signalized intersection recently reconstructed as part of the City’s West Avenue Bridge project. The current configuration of the intersection was determined during the Project Development and Environment (PD&E) study as a result of comprehensive traffic forecasting, trip assignment, and modeling. The PD&E study was approved by Miami-Dade County and the Federal Highway Administration in 2012. Prior to the bridge construction, the intersection was unsignalized with a southbound stop sign for West Avenue.

The north leg of the intersection currently consists of a single lane in each direction and on-street parallel parking on both sides. The north leg of the intersection is approximately 42 ft. wide (including gutters) and consists of two (2) 12 ft. wide travel lanes and two (2) 8.5 ft. wide parallel parking lanes. At the intersection, southbound motorists are permitted to turn left, right, or travel through from the single southbound lane.

Given that Dade Boulevard is a County roadway, the intersection of West Avenue and Dade Boulevard is under the jurisdiction of Miami-Dade County.

This item was discussed at the July 15, 2020 NQLC meeting. At the meeting, staff explained that in order to determine the feasibility of the requested left turn signal, an analysis would need to be conducted, including:

• Geometric analysis and stopping sight distance

• Turning movement counts

• Vehicular, pedestrian, and bicycle counts

• Traffic modeling/intersection level of service analysis (with and without a dedicated southbound left turn lane)

At the meeting, staff also explained that West Avenue is designated as a bicycle corridor in the City’s adopted Transportation Master Plan; and the Transportation and Mobility Department is proposing to extend the existing West Avenue Bridge green bicycle lanes north to 20 Street. As such, bicycle lanes were included in the traffic analysis for a dedicated southbound left turn lane to ensure that both improvements can be accommodated within the existing right-of-way.

Pursuant to the NQLC’s recommendation at the July 15, 2020 meeting, Transportation and Mobility Department staff performed a geometric analysis and a sight distance analysis for the intersection to determine the feasibility of a dedicated southbound left turn lane.

The first step of the analysis included a review of the current pavement width of the north leg of the intersection of West Avenue and Dade Boulevard to determine if the current pavement width can accommodate the minimum desired cross section consisting of: two (2) 10 ft. travel lanes (one in each direction), one (1) 10 ft. southbound left turn lane, and two (2) 5 ft. bike lanes with 2 ft. buffers for protection.

Given that the existing pavement width is approximately 39 ft., staff confirmed that the north leg of the intersection cannot accommodate the desired cross section including the proposed protected bicycle lanes and a dedicated southbound turn lane. The minimum pavement width required to accommodate the desired cross section is 44 ft.  It is worth highlighting that at least seven (7) on-street parking spaces would be impacted with the addition of the bicycle lanes or southbound left turn lane. These parking spaces cannot be mitigated if removed; however, this neighborhood is served by a public parking garage on Bay Road. Given that West Avenue was raised as part of the Sunset Harbour Neighborhood Improvement Project in 2017, further review is required to ascertain if the road could be widened or if reconstruction of the intersection and a portion of West Avenue would be necessary to address harmonization between the businesses and the road.  

Given that deliveries for various businesses (Publix, Fresh Market, etc) in the Sunset Harbour neighborhood are performed by large trucks, the design vehicle used in the analysis was a WB-67 Truck (67 ft. in length between the front axle of the truck and rear axle of the trailer). Using the as-built plans for the intersection, staff laid-out the turning radius for this type of truck. The analysis determined that the front of a truck making a left turn from southbound West Avenue into eastbound Dade Boulevard would encroach into the outside eastbound lane of Dade Boulevard, and the rear left wheel of the truck would significantly encroach into the westbound left turn lane on Dade Boulevard (Attachment).

In analyzing the existing signalization at the intersection, it was found that the southbound left turn on West Avenue would need to be protected (i.e. left turn arrow) to avoid conflicts at the center of the intersection between the southbound left turning vehicles and the West Avenue northbound through movement. Modifications to the mast arm facing southbound West Avenue traffic may be necessary in order to accommodate the additional signal heads required for a protected left turn signal. To determine if modifications to the mast arm are necessary, additional analysis, including structural, is required by Miami-Dade County.

It is important to note that even if a dedicated southbound left turn lane were to be geometrically feasible, a left turn lane warrant analysis is required to ascertain the need for a dedicated left turn lane based on left turn traffic volumes, delays, and accidents.