2.3.1. Smart Waste Bins

IoT-enabled waste bins are equipped with sensors that can detect the fill level of the bin. These sensors can use ultrasonic, infrared, or weight-based technologies to measure the waste level. When the bin reaches a certain threshold, it sends an alert to waste collection teams, optimizing the collection process by reducing unnecessary trips and preventing overflow [80].

#### 2.3.2. Route Optimization

IoT devices on waste collection vehicles enable real-time tracking of their location and status. These devices can use GPS technology to find the most efficient routes for waste collection, considering factors such as real-time traffic conditions and the fill levels of individual waste bins. Optimized routes reduce fuel consumption, emissions, and operational costs [81].

#### 2.3.3. Environmental Monitoring

IoT sensors can be deployed in landfills to monitor environmental conditions such as methane emissions, temperature, and air quality. Real-time monitoring helps in early detection of potential issues and allows for timely mitigation actions, ensuring compliance with environmental regulations [82].

#### 2.3.4. Recycling Management

IoT applications can facilitate the separation and sorting of recyclable materials. Smart recycling bins equipped with sensors can help users identify the correct recycling category for their waste items, promoting proper recycling practices [83].

#### 2.3.5. Public Awareness and Education

Smart waste management IoT applications can also be used to raise public awareness about waste management and encourage responsible waste disposal behaviors. Interactive displays on waste bins or smartphone apps can provide information about recycling guidelines, waste reduction tips, and the environmental impact of different waste disposal methods [84].

### 2.3.6. Data Analytics

IoT-generated data from waste bins, collection vehicles, and landfill sensors can be analyzed to identify patterns and trends in waste generation, collection efficiency, and recycling rates. This data-driven approach allows municipalities and waste management companies to optimize their operations further and make informed decisions [85].

#### 2.3.7. Remote Monitoring and Maintenance

IoT devices enable remote monitoring of waste management infrastructure, such as waste compactors and incinerators. This allows for proactive maintenance and reduces downtime, ensuring that waste management systems operate efficiently [86].

#### *2.4. Public Safety*

The goal of public safety is to create a safe and secure environment for all. This includes protecting people from crime, fire, and other hazards. Public safety also includes ensuring that people have access to emergency services when they need them. There are many different organizations that play a role in public safety. These include law enforcement agencies, fire departments, emergency medical services (EMS), and disaster response agencies [87]. These organizations work together to prevent crime, respond to emergencies, and protect the public from harm. Public safety IoT applications use connected devices and sensors to enhance public safety and security [88]. Some public safety IoT applications follow.

#### 2.4.1. Traffic Management

Monitoring traffic conditions, detecting accidents or incidents, and optimizing traffic flow can improve response times for emergency services [88]. Traffic management applications are essential tools used to ensure the safety of road users and pedestrians, as well as to improve the efficiency of traffic flow. Here are some examples of traffic management and public safety applications:

1. Intelligent Traffic Systems (ITS)

ITS are systems that use advanced technologies such as sensors, cameras, and communication networks to monitor and manage traffic on roads [89]. These systems provide real-time information to drivers about traffic conditions, road closures, accidents, and other incidents, enabling them to make informed decisions about their routes and travel times.

2. Automated Traffic Enforcement (ATE)

Systems use cameras and sensors to automatically detect and enforce traffic violations such as speeding, red-light running, and illegal parking [90]. These systems are often used to improve public safety by reducing the number of accidents caused by irresponsible driving.

3. Emergency Vehicle Prevention (EVP)

EVP systems are used to provide emergency vehicles, such as ambulances and fire trucks, with high priority access to intersections. These systems use transmitters on emergency vehicles to communicate with traffic signals [76], allowing them to change to green lights and clear the way for the emergency vehicle.

4. Pedestrian Detection Systems (PDS)

PDS systems use sensors and cameras to detect pedestrians in crosswalks and alert drivers to their presence [91]. These systems are especially useful in areas with high pedestrian traffic, such as urban centers and school zones.

5. Variable Message Signs (VMS)

VMS are electronic signs that display real-time information about traffic conditions, road closures, and other relevant information to drivers. These signs are used to provide drivers with up-to-date information that can help them make immediate decisions about their routes and travel times [92]. In general, these traffic management and public safety applications are essential tools for ensuring the safety of road users and improving the efficiency of traffic flow.
