Fishtown Roundabout Construction and Intersection Safety Improvements

Our Client’s Challenge

The intersection of Frankford Avenue, Trenton Avenue, and York Street in Philadelphia’s Fishtown District was a six-legged signalized junction located in a crowded urban area. Its design was difficult to manage and had limited signal-head visibility due to the lack of signal mast arms. The City of Philadelphia prioritized a new single-lane roundabout project for increased intersection safety and to lower the roadway’s footprint and complexity for road users and pedestrian infrastructure.

A roundabout, also known as a traffic circle, rotary, or traffic island, is a type of intersection design used in road traffic management. It consists of a circular junction in which road traffic flows around a central island, typically in a counterclockwise direction. Roundabouts are designed to facilitate the smooth and continuous flow of traffic while minimizing the risk of collisions.

They are considered safer than traditional intersections for several reasons, including:

Reduced speed.
Continuous traffic flow.
Fewer conflict points.
Reduced severity of collisions.
Improved visibility.
No red-light running.
Lower risk of fatalities.

The continuous traffic flow in roundabouts reduces the need for frequent stops and starts, which can reduce congestion and improve fuel efficiency.

Our Solution

Gannett Fleming provided professional consulting engineering services to the City of Philadelphia Department of Streets through an on-call general engineering services agreement for varied transportation-related work. For the contract’s first assignment, we provided construction management and construction inspection services for the Fishtown Roundabout Construction and Intersection Safety Improvements Project. The new roundabout includes:

Removal of the existing traffic signals.
Installation of new street lighting.
Curb line reconfigurations and islands.
New signing and line striping.
Upgraded ADA curb ramps.

Frankford Avenue is a state route with annual average daily traffic (AADT) ranging from 8,500 to 9,000 vehicles, while the other roadways have lower quantities. Truck movements at the intersection greatly impacted the geometric and operational design decisions. A distinctive feature is the large central island, which is wide enough for trucks to pass through if required. It was constructed to be sturdy enough to support tractor trailers and made of reinforced plastic.

The geometric design includes:

ADA curb ramps.
Drainage.
Roundabout components.
Splitter islands.
Truck aprons.
A main central island.

Through the design progression, the team decided to regrade half of the intersection to provide a curb reveal and ADA-compliant sidewalk slopes near an outside truck apron on Frankford Avenue. This project required the Pennsylvania Department of Transportation (PennDOT)’s review and approval in the form of a highway occupancy permit submission.

This project supports the City of Philadelphia’s Vision Zero goals, reducing the number of traffic deaths to zero. Compared to a signalized intersection, PennDOT has shown that roundabouts help mitigate the risk of crashes, reducing apparent serious injuries by 76% and total crashes by 9%.

Key Features

Roadway and roundabout enhanced LED lighting.
Speed cushions to slow motorists on the approach of the roundabout on York Street and planned for construction on Frankford Avenue.
New signage and pavement markings.
Grass mountable central island.
Entry points designed to slow vehicles and improve safety.
New sidewalks and pedestrian-friendly ADA ramps.

Outcomes

Supports the City of Philadelphia’s Vision Zero goals, reducing the number of traffic deaths to zero.
Complete streets design approach enables safer pedestrian and cyclist approaches.
Enhanced accommodations for trucks and public transportation approaching the intersection.
Capacity for more vehicles than similarly sized signalized intersections during peak traffic conditions.

Awards & Recognition

Project of the Year, 2022, Mid-Atlantic Section of the Institute of Transportation Engineers (MASITE).
Diamond Award, 2023, American Council of Engineering Companies (ACEC) Pennsylvania Section.