Traffic Signal Projects

Traffic Signal Upgrades/Revisions

The City of Pittsburgh's Department of Mobility & Infrastructure (DOMI) is responsible for the maintenance and operation of 615 traffic signals and 92 flashing devices. DOMI is routinely replacing, upgrading, and assessing the need for traffic signalization on an ongoing basis. These improvement projects are funded through various sources, including the City of Pittsburgh Capital Budget, developer commitments and state-funded grants. This engage page is the hub for small-scale, city-wide traffic signal projects.

Descriptions of typical design features implemented through traffic signal upgrade projects are shown below. The actual list of individual improvements at each intersection are included under their respective pages.

Vehicular Signal Heads

Retroreflective Backplates

Backplates on traffic signals improve visibility of the lights by placing them in a controlled-contrast background. Retroreflective borders added to the backplate improve visibility in both daytime and nighttime conditions. This addition is also beneficial during power outages when signals may otherwise be dark and less noticeable.

12" Signal Head

Image of Traffic Signals at Intersection

All new City of Pittsburgh traffic signals will be installed with 12” diameter lenses. Studies have shown that increasing the signal lens size from 8” to 12” can have a significant reduction in vehicular crash frequency.

Flashing Yellow Turn Signals

Source: MUTCD

Unlike traditional signals that employ "yield-on-green" indications, Flashing Yellow Arrow turn signals (FYA) feature a flashing yellow arrow in addition to standard solid red, yellow, and green indicators. FYA signals otherwise function identically to traditional signals. The implementation of the yellow arrow helps make intersections safer, as the arrow is more easily understood by drivers, and reduces delays when traffic is light.

References

FYA Fact Sheet - PENNDOT
PDF (456.19 KB)

Pedestrian Signal Heads

Pedestrian Countdown Timers

These installations are a standard pedestrian signal head with an added display showing a countdown of the remaining crossing time. This assists pedestrians and improves safety by sharing information about the amount of time left to safely cross the street before traffic signals change.

Leading Pedestrian Intervals

The City of Pittsburgh typically implements "Leading Pedestrian Intervals" (LPIs) as part of traffic signal upgrade projects. Also known as “pedestrian head start” or “delayed vehicle green,” this application improves pedestrian safety by allowing them an advanced start into the intersection, enhancing visibility and helping reduce conflicts with turning vehicles. The implementation of an LPI is not possible without having pedestrian signal heads in place.

References

Accessible Pedestrian Signals

These are device installations that share information about the WALK and DON'T WALK phases at signalized intersections in non-visual manners for those who have impaired vision. These methods include audible instructions, vibrating buttons, etc.

Vehicular Detection

The City of Pittsburgh, in certain instances, will use partial or full traffic responsive control systems. These systems depend on their ability to sense traffic for efficient traffic control. DOMI currently uses non-pavement invasive detection systems, using radar or video image detectors.

LED Street Lighting

HSP and LED street lights — *Source: Street Lighting Division, Streets Department, City of Philadelphia*

During design processes, DOMI assesses the need to add additional LED streetlights to traffic signal projects. The City currently uses a mixture of High-Pressure Sodium (HPS) and LED light installation. The difference, as shown in the picture above, between older HPS street lights (left) and updated LED light installations (right) is stark. Because they rely on older technology, HPS lights are less durable and energy efficient than LEDs. Additionally, the updated LED lighting provides increased visibility, improved safety for all users, and faster lighting repair/replacement times.