## 2 Methodology
### Instantaneous Emissions Acquisition  
Pollution emissions from vehicle exhausts during a trip were obtained using a dynamometer. This is the usual method to characterize instant emissions through the engine load, acceleration, and speed of vehicles. These data were utilized to obtain emissions regression models.  
In this study, a smartphone Android app, \"BotlnckDectr\" [20], was employed to measure the CO\({}_{2}\) pollutant emitted when a vehicle traversed a route. The route selected for this study started at 33.9761\({}^{\circ}\) N, 71.4453 E\({}^{\circ}\) and ended at 34.0020\({}^{\circ}\) N, 71.4851 E\({}^{\circ}\). The origin of the route was Phase 2, Hayatabad, and the destination was the University of Engineering and Technology (UET) Peshawar, KPK, Pakistan; the morning trip was from 08:39 a.m. to 08:54 a.m., as shown in Figure 2. In the evening, the trip route was from UET Peshawar to Phase 2 Hayatabad, Peshawar, from 05:20 p.m. to 05:35 p.m., as shown in Figure 3. The evening trip was observed on Monday, 19 January 2020. The total length of the morning route was 7.7 km, and the evening route was 7.1 km long. In the morning, the total travel time on this route was 14 min, while the evening trip lasted 17 min. The congested traffic occurred on the N5 road, indicated with a red color in Figure 3. The blue color indicates the free flow and smooth traffic. The traffic flow was heterogeneous, with no lane discipline followed by the drivers. Data and images in Figures 2 and 3 are courtesy of Google Maps. The route was tested during weekdays from 19 January 2021 to 22 January 2021.  
Figure 1: The research methodology. The colored lines show the microscopic and macroscopic view of the idea implemented.  
the best performance. Usually, the intake air temperature was 30 to 70 \({}^{\circ}\)C. An ELM 327 adapter (OBD-II) was utilized in this research to transmit the data from the vehicle's ECU. OBD-II transferred data at 5 s through Bluetooth connectivity from the ECU to BotluckDectr (Android application). In real time, BotluckDectr received sensor data from the vehicle. In addition to the acquired data, the time and location of a vehicle from a smartphone's GPS were communicated through a cellular network to Amazon Web Services DynamoDB. Amazon Web Service (AWS) is a subsidiary of Amazon that provides a suite of cloud computing services, including storage, computing power, and databases. These services are offered over the internet, allowing organizations to build and run applications and store data in the cloud rather than on physical servers located in their own facilities [20].  
Our choice of AWS was influenced by multiple design considerations, including AWS' reliability and scalability. However, other important considerations were communication and data security. AWS provides a wide range of services for data protection both while in transit (as it travels to AWS) and at rest (while stored at AWS) through different services such as identity and access management (IAM), certificate manager, Amazon GuardDuty, to name a few [22]. All data from remote devices were transmitted to AWS through a TLS connection using HTTPS, MQTT, and WebSocket protocols, ensuring security by default while in transit.