Sometimes known as a car accident or road accident, a traffic accident is an event in which one or more vehicles crash into other vehicles, pedestrians, animals, or fixed objects like trees and barriers. Driver negligence, mechanical faults, unfavourable weather conditions, and the hazardousness of the road can be some reasons for these accidents.

The nature of traffic accidents can range from mild fender-benders to major crashes that may lead to serious injuries or death. In such cases, emergency services are usually called to the scene to provide help, remove the wreckage from the road, and determine the cause of the accident.

Conducting an investigation into a traffic accident involves a series of steps to determine the cause, assign fault, and gather evidence for potential legal action.

The following is an overview of the steps involved:

• Scene Assessment: The first step is to secure the scene to prevent any further accidents and ensure the safety of those involved. The scene is then assessed for any immediate hazards, such as leaking fuel or unstable vehicles. Details such as the position of the vehicles, position of the injured or deceased, skid marks, road conditions, weather, and visibility are documented.
   
• Medical Assistance: If there are any injured parties, they should be attended to and medical assistance is arranged if necessary. Injuries and treatments are documented for future reference. Injured should be taken to the nearest medical facility and dead body if any shifted to the hospital for post mortem and further examination.
   
• Informing the Family Members: The family members of the injured or victim of the traffic accident should be informed about the accident immediately.
   
• Diversion of Traffic: If the need for diversion of traffic is felt for proper management of the traffic accident, the same should be done in coordination with the local police station and Traffic Headquarters.
   
• Seizure: In incidents of traffic collisions, law enforcement typically seizes a variety of evidence to effectively investigate the occurrence and establish the sequence of events leading up to the crash. This evidence may involve seizing the accident vehicle, retrieving data from Event Data Recorders (EDRs) in vehicles, commonly referred to as black boxes, to analyse factors such as speed, braking patterns, and other operational parameters.

In addition, footage from dashcams in involved or nearby vehicles can serve as crucial visual evidence, providing insights into the moments leading up to the collision. Along with these technological resources, the police also gather witness statements, photographs of the accident scene, and physical evidence such as debris and skid marks to accurately reconstruct the events.

Furthermore, if intoxication or distraction is suspected, the authorities may conduct tests such as blood alcohol content (BAC) tests or examine cell phone records to determine if alcohol or mobile phone use played a role in the accident. Thorough documentation of driver information, including licenses, registrations, and insurance details, is also a standard protocol. By collecting and analysing these various forms of evidence, law enforcement aims to determine the circumstances of the accident, establish fault, and ensure equitable outcomes for all parties involved.

• Normalising of Traffic Movement: As soon as possible normal traffic movement should be restored by clearing the road after taking necessary formal steps regarding investigation of the case and collection of all evidences from the scene of crime.
   
• Collection of Complaint: A complaint should be collected either from the victim or their relatives or any other witness to lodge a formal complaint and initiate a case.
   
• Witness Statements: Witnesses to the accident are interviewed to gather their accounts of what happened. Their contact information is recorded for future reference.
   
• Photographic Evidence: Photographs of the accident scene are taken from various angles, including vehicle damage, road conditions, and relevant signage. Rough sketch map of the scene of crime may also be drawn.
   
• Vehicle Examination: The vehicles involved in the accident are examined to assess damage and potential mechanical faults. Information such as ownership, registration, and insurance are also collected.

Data Collection: Any available data, such as black box recordings, GPS data, or surveillance footage from nearby cameras, is obtained.

The Event Data Recorder (EDR), commonly referred to as the 'black box,' found in vehicles, typically holds data regarding the vehicle's actions leading up to and during a collision. This information can encompass details like speed, engine performance, braking, throttle usage, steering angle, airbag deployment, seatbelt usage, and in some cases, audio and video recordings if the technology allows. Analysing the data from the black box is essential in comprehending the events that led to the accident and can offer significant findings for reconstructing the crash and conducting safety assessments.

The GPS data from a vehicle usually includes details on its position, velocity, orientation, elevation, and sometimes timestamps indicating the time each position was logged. This information is collected by the vehicle's GPS receiver, which communicates with satellites to determine the exact location on the planet. Apart from fundamental location and motion data, contemporary GPS systems may also retain supplementary information like travelled routes, visited waypoints, and other navigational details. This data can serve various purposes, including keeping a record of navigation history, managing fleets, monitoring vehicle movements, and studying driving behaviour.

• Police Reports: Copies of police reports filed at the scene, including statements from involved parties and officers' assessments, are obtained.
• Collection of Medical Reports: The medical report/injury report/post mortem report should be collected from the hospital where the victim was treated or expired to ascertain the nature of injuries suffered.
• Accident Reconstruction: Physical evidence, vehicle damage, and witness statements are analysed to recreate the accident scenario. Utilizing accident reconstruction techniques and software is important in creating a detailed reconstruction of the accident sequence.
• Interview Emergency Responders: Interviewing emergency responders, such as police officers, paramedics, and firefighters who responded to the accident, can provide additional insights and information about the incident.
• Expert Consultation: Consult with accident reconstruction experts, engineers, or medical professionals to analyse evidence and provide expert opinions.
• Legal Consultation: Legal professionals are consulted to understand the legal implications of the evidence gathered. Liability is determined based on local traffic laws and regulations.
• Report Compilation: Compile all evidence and reports into a comprehensive document to be used for legal proceedings.
• Legal Proceedings: In the event that it is deemed necessary, utilize the collected evidence in any legal proceedings, including but not limited to insurance claims or court cases. If needed, offer testimony as an expert witness.
• Follow-Up: Remain diligent in following up on the case, offering any additional information or testimony as deemed necessary. The complexity and required actions in each case may vary based on factors such as the severity of the accident, the number of vehicles involved, and local regulations.
• Driver History Check-up: Conducting a driver history check involves a thorough review of driving histories, including any previous accidents, traffic violations, and current license status of the drivers involved. This is essential in determining the level of responsibility and potential liability of each party. It may also be checked whether the driver was drunk or under the influence of any drug.
• Insurance Documentation: Obtaining insurance information for all involved parties is another crucial step in the investigation process. This allows for a determination of coverage and potential liability, as well as providing important information for potential legal proceedings.
• Evaluate Road Design: Assessing road design and conditions is also important in determining contributing factors to the accident. This includes evaluating signage, lighting and potential road defects that may have played a role in the incident.
• Analyse Vehicle Maintenance: Reviewing maintenance records for the vehicles involved can provide valuable insight into any mechanical issues that may have contributed to the accident.
• Cell Phone Records: Obtaining cell phone records for the drivers involved can help determine if distracted driving was a factor in the accident.
• Review Medical Bills: Examining medical bills and expenses related to injuries sustained in the accident is necessary to understand the full impact of the incident on those involved.
• Coordinate with Legal Counsel: Working closely with legal counsel is crucial in understanding the legal implications of the accident and preparing for potential litigation.
• Liability Assessment: Determining liability is a key aspect of the investigation process, and is based on evidence, witness statements, and applicable laws and regulations.
• Draft Accident Report: Compiling all gathered evidence, analysis, and findings into a comprehensive accident report is essential in documenting the investigation process and its outcomes.
• Negotiate Settlement: Engaging in negotiations with insurance companies or legal representatives is necessary to reach settlements for property damage and injury claims.
• Expert Testimony: Providing expert testimony in legal proceedings may be required to explain findings and analysis.
• Follow Up and Documentation: Maintaining thorough documentation of all investigation activities and outcomes is important for future reference or legal purposes.

Giving medical attention to the driver, if required, is more important, as the driver of the vehicle might also get injured during the traffic accident.

Not all traffic accidents result in detention. In less severe scenarios where there are no injuries or significant property damage, and no indication of criminal behaviour, drivers may be issued citations or traffic tickets. Ultimately, the decision to take a driver into custody after a traffic accident is at the discretion of law enforcement and is dependent on the particular circumstances of each individual case.

The decision to take drivers into custody following a traffic accident is influenced by a variety of factors, such as the gravity of the incident, the presence of harm or fatalities, and the possibility of unlawful conduct like operating a vehicle under the influence (OVI) or reckless driving. In situations where there are serious injuries or fatalities, law enforcement may opt to arrest drivers suspected of being responsible to aid in their inquiries, gather evidence, and ensure their attendance at legal proceedings. Moreover, if there is reasonable cause to believe that a driver was impaired by drugs or alcohol, they may be apprehended for OVI.

This comprehensive approach helps ensure a thorough investigation of the traffic accident case, facilitating accurate determination of liability and fair resolution of claims.