Introduction
“Accessible pedestrian signals (APS) are devices that communicate information about the walk and don’t walk intervals at signalized intersections in non-visual formats to pedestrians who are blind or who have low vision”. Accessible pedestrian signals play a crucial role in ensuring safety and accessibility for all individuals, primarily those with disabilities. As cities strive to enhance their infrastructure and comply with the 2023 PROWAG guidelines, the two main types of APS may be difficult to navigate. Independent APS and networked APS have many similarities but also a few vital differences. While both aim to facilitate pedestrian navigation, they do so through different mechanisms, each with its own set of advantages and limitations. By delving into the nuances of these two systems one can better understand their similarities and differences enabling one to make an educated decision about which is better for any intersection one may come across.
What Makes a Push Button and Accessible Pedestrian Signal?
To be considered an APS system, the system must provide pedestrians with audible information about the walk and don’t walk phases. Audible information from an APS consists of two different types depending on the region: verbal messages which can include words like “wait to cross” or “walk sign is on to cross”, and tones which are standard percussive tones equated to each verbal message. Typically, APS also provides vibrotactile walk indications paired with an arrow installed on the pushbutton for visual indications.
Independent APS
As an APS system, independent APS still provides pedestrians with audible, visual, and tactile indications but it is referred to as an independent system due to the way that it is connected to the traffic system. Independent APS is often referred to as a 4-wire system as 2 wires connect the pedestrian signal head to the button and two wires connect the button to the traffic control cabinet. These signals operate autonomously at each intersection, functioning independently of other signals in the vicinity. Each unit is responsible for managing pedestrian crossings based on local conditions, such as traffic flow and pedestrian demand.
With PedSafety’s Guardian® lineup of independent APS systems, an APS is provided with power and indications from the pedestrian signal head through SPI (Signal Power Interface). Within the button itself is where all the main information is stored such as data storage, settings, configurations, etc. and the SPI is housed within the pedestrian signal head, routing signals back to the button.
The system is considered independent as it is cabinet-free, meaning that no products are required to be placed within the traffic control cabinet to operate each button. It is a 1 to 1 relationship between the pedestrian signal head and the APS itself.
Networked APS
On the other hand, networked APS systems have much more flexibility in the way that one’s intersection is set up. Often referred to as 2 wire systems, networked APS systems have all the functionality required of APS with the added bonus of being fully adaptable to any intersection.
PedSafety’s WiAAPS® lineup of networked APS systems are 2-wire systems powered by the existing two field wires, or in cases of non-accessible field wires, can be powered with no field wires through from the pedestrian signal head SPI, meaning no wires would run back to the traffic control cabinet. WiAAPS® is comprised of the WiAPC/WiAPC-C (controller) and the WiAPB (push button). The WiAPC/WiAPC-C maintains continuous communication with each WiAPB within a network-based control system and operates wirelessly through secure 900MHz narrow-band communication. Users are guaranteed both safety and security as well as reliability with the WiAAPS®’ mesh network protocol.
As a networked APS system, the intersection is designed to be remotely configured and monitored. And is so adaptable because the controller can be either a card rack or shelf mount, the system can be powered through field wires, SPI, or solar power, and the system has the capability to control up to 16 buttons in the intersection across 8 different pedestrian phases.
Which is a Better Choice?
Overall, when looking at the differences between independent and networked APS, the main standout between the two is the adaptability of a networked APS system. This system can seamlessly integrate into existing intersections, rather than requiring modifications to accommodate it, making it the ideal choice for intersections that are preestablished or to lay a foundation for adaptability with future intersection changes.
While an independent APS system is much more arbitrary, the complexities of a networked system display intricacies that outdo the capabilities of a more simplistic system. With the initial cost of a networked system being higher than that of an independent APS system, the overarching cost of the system as a whole makes it a more economical choice as it provides users with cost-saving powering capabilities as well as being able to transfigure into what the intersection needs at the time rather than having to make costly changes to adapt to the product itself.
Conclusion
In conclusion, while both independent and networked accessible pedestrian signals serve to enhance safety and accessibility at intersections, they differ in their operational mechanisms and adaptability. Independent APS offers simplicity and a direct 1-to-1 relationship between the pedestrian signal head and the APS itself. In contrast, networked APS systems provide greater adaptability, seamlessly integrating into existing intersections and allowing for remote configuration and monitoring. Despite the higher initial cost, the long-term benefits of a networked system, including cost-saving powering capabilities and adaptability to changing intersection needs, make it a more economical choice.
Ultimately, the decision between independent and networked APS depends on factors such as intersection setup, budget considerations, and the need for future adaptability. By carefully considering these factors, stakeholders can ensure the effective implementation of APS to improve pedestrian safety and accessibility in urban environments. For more information on the intricacies between the two systems, contact our sales team or your local distributor.