Traffic police

A Nigeria Police Force officer directing traffic at a busy intersection

One of the oldest and most basic forms of traffic policing is directing traffic. This is conducted by a traffic officer (usually only one) who stands in the middle of an intersection, using hand signals and occasionally also a whistle, a handheld traffic sign (usually a stop sign), or a handheld light stick to manage the flow of vehicles and pedestrians. The officer directing traffic is usually a foot patrol officer or an auxiliary officer, though officers with vehicles may also direct traffic, parking their vehicles out of the way. Officers directing traffic typically wear high-visibility clothing to provide visibility and avoid being struck by traffic, ranging from brightly colored uniforms (historically a white patrol cap or helmet with gloves) to neon-colored vests and coats with retroreflective strips.

Though common worldwide before traffic signs and traffic lights became commonplace, traffic direction is now rare in places where traffic lights are the primary mode of traffic management, where it is mostly limited to incidents where roadways are closed or obstructed, traffic is heavier than usual, or traffic lights are disabled or otherwise unavailable, such as during a power outage or at the scene of a traffic collision. Traffic direction continues to be a mainstay in places where traffic lights and signs are not used, or where traffic is so dense that directing traffic is more effective than relying on lights and signs alone.

A California Highway Patrol traffic unit conducting a traffic stop

One of the most common forms of traffic policing in the modern day is vehicular enforcement. This is conducted by police officers using vehicles, typically cars or motorcycles but occasionally also aircraft or watercraft, who directly enforce vehicular traffic. Vehicular enforcement is often very similar to regular police patrols, and may be a standard police responsibility in some agencies. Vehicular enforcement usually consists of the enforcement of speed limits, registration and licensing, driving under the influence, commercial vehicle inspection, and other vehicle-related laws and crimes. The most common methods of vehicular enforcement are traffic stops, checkpoints, and "watching traffic" along the shoulder of roadways using radar speed guns.

Some roads may be patrolled by aircraft, a declaration usually posted along such a roadway by the agency operating said aircraft. Though some motorists view this as mere deception used to promote slowing down, police aircraft actually do patrol some freeways, albeit rarely due to the costs in operating aircraft for lengthy periods.[5][6] To measure a vehicle's speed, the pilots calculate the time it takes to travel between a set of road markings. Should the pilots determine the vehicle is speeding or violating a law, they follow it until a police unit in a land vehicle arrives to initiate a traffic stop.[5][6]

A dispatch center used by the Nevada Department of Transportation and Nevada State Police to monitor highways

Remote traffic enforcement is conducted using traffic enforcement cameras typically installed and managed by a transportation authority, highway authority, or police agency along roadways. These camera feeds are then monitored for visible crimes or incidents such as speeding, reckless driving, or traffic collisions, to which the proper services are then dispatched if needed. Some traffic cameras can automatically read plates to check for registration and licensing infractions or wants and warrants, or even fine the registered owner of the vehicle without having to dispatch a police unit to issue a ticket.

In the 2010s, the Congolese National Police deployed automated traffic police robots. Created by Thérèse Kirongozi, an engineer from the Democratic Republic of the Congo,[7] the tall solar-powered aluminum robots are positioned in intersections and are able to rotate, but cannot actually move; rather, they contain closed-circuit television cameras in their "eyes" that record offenders for human traffic officers to handle.[8] The robots also carry red and green lights to direct traffic, and can speak to pedestrians and help them cross roads.[9][10] Five robots were installed in intersections in Kinshasa by 2015, with thirty more planned for highway patrol purposes.[9]

Some traffic officers are not part of police agencies, and are instead part of transportation authorities, highway authorities, or regulatory boards. They often work alongside police, and may call upon them to handle emergencies or road crimes.

In the United Kingdom, England's National Highways employs traffic officers, as does the Welsh Government, who also employ traffic officers; both are responsible for traffic management and roadside assistance on trunk roads in their respective jurisdictions. In the Philippines, the Land Transportation Office (LTO) and Land Transportation Franchising and Regulatory Board (LTFRB), the agencies under the Department of Transportation, enforces a range of vehicular laws. In the United States, some department of transportation (DOT) agencies are able to direct traffic, provide roadside assistance, and enforce traffic laws.

In some instances, civilians and unsworn personnel may be enlisted by police for auxiliary purposes, including traffic policing, while others may take it upon themselves to direct traffic in the absence of the proper authorities. For example, during the Northeast blackout of 2003, citizens in Toronto and New York City directed traffic while traffic lights were disabled.[11][12] However, in some jurisdictions such as Ontario, such practices are illegal, and only law enforcement and authorized personnel can direct traffic due to liability concerns.[13][14]

In the United States, there have been some efforts to transfer traffic stop authority to some DOTs as part of police reform initiatives, most prominently in Berkeley, California, which planned to establish "BerkDOT" to enforce minor traffic violations while still allowing the Berkeley Police Department to handle major violations and road crimes.[15] Proponents argue that shifting traffic enforcement from police to DOTs would reduce the chance of escalation in traffic stops, keep traffic enforcement related to traffic without police criminal record checks, and allow police to focus more on criminal concerns.[15][16][17]