Police Cruiser

Overview

A police cruiser is a patrol vehicle built from a pursuit-rated car and then loaded with the equipment an officer needs to work from it. The starting point is the Pursuit Vehicle, a police-package sedan or SUV that the manufacturer has already uprated for the duty cycle. On top of that go the visible identifiers and tools: an Emergency Lighting package, a Siren & PA, a Communications radio, a Mobile Data Terminal computer, a Partition & Rear Cell for transporting people in custody, a Patrol Equipment of patrol gear, and an Auxiliary Power system large enough to power all of it. The defining demand on a cruiser is not top speed but endurance: it must idle for hours running every accessory, then pursue at speed, without overheating or going flat.

The pursuit vehicle

The Pursuit Vehicle differs from a civilian car in cooling, brakes, suspension, and electrical capacity. The Pursuit Engine is a V6 or V8 calibrated for sustained high-speed running and long idle, fitted with a Oil Cooler and an engine-hour meter. Because a cruiser may sit running all shift, the Heavy-Duty Cooling pack pairs a large Radiator with extra Auxiliary Fan units to hold temperature at idle. The Pursuit Suspension stiffens springs and adds a bigger Anti-Roll Bar for stability under load and at speed, and the Severe-Duty Brakes use oversized vented discs with Brake Cooling Duct airflow so repeated stops from speed do not fade. These are the changes that earn a vehicle its pursuit rating.

Warning lights and siren

The Emergency Lighting package is what makes the cruiser a warning vehicle. A roof Lightbar of LED LED Module heads in red, blue, and amber is supplemented by Grille Light and Surface Light around the body for visibility from every angle, plus Takedown Light that flood a stopped vehicle. A Flash Controller drives all of them through synchronised patterns. The audible side is the Siren & PA: a Siren Amplifier generating wail, yelp, and air-horn tones into grille-mounted Siren Speaker units, controlled from the Siren Control Head which also switches the lights, with a PA Microphone for public address. Officers cycle siren tones at intersections because a changing tone is easier to localise than a steady one.

Communications and computing

Two systems connect the officer to the wider force. The Communications radio is the voice link: a Mobile Radio transceiver, often P25 digital and encrypted, with a Radio Control Head for channel selection and a Radio Microphone. The Mobile Data Terminal is the data link: a Rugged Computer on a Laptop Mount between the seats, connected over a Data Modem, running computer-aided dispatch, plate and licence lookups, and report writing. The mobile data terminal moved much routine traffic off the voice channel: an officer can run a plate silently rather than tying up the radio, which is why nearly every modern cruiser carries one.

The prisoner compartment

A cruiser must safely carry people in custody, so the rear is rebuilt as a secure cell. The Partition & Rear Cell adds a Partition Cage of steel and polycarbonate behind the front seats, a seamless moulded Prisoner Seat with no crevices to hide contraband and a surface that hoses clean, and guards over the rear so a detainee cannot operate the doors or windows: Window Guard and Door Guard panels disable the rear controls. The front seats are usually moved forward and reshaped to give a belted officer room to work past a duty belt.

Equipment and auxiliary power

The patrol fit-out lives in the Patrol Equipment: a Equipment Console of switch panels and the radio, a locked Weapon Mount, a In-Car Camera recording stops and the rear seat, pillar Pillar Spotlight lamps, and often a Traffic Radar. All of this draws far more than a stock charging system can supply, so the Auxiliary Power system adds a High-Output Alternator, a Dual Battery System arrangement, a fused Power Distribution Panel panel feeding each device, and a Idle Controller that runs the engine as needed to keep batteries charged and the cabin climate-controlled while the car is parked and locked. The electrical upgrade is what most distinguishes a built cruiser from the car it started as. A patrol vehicle may draw two hundred amps or more with every light flashing, the siren sounding, the radio transmitting, and the computer running, all while the engine turns at idle where a standard alternator produces a fraction of its rated output. Builders therefore start from the police-package charging system and add to it, sizing the High-Output Alternator and the Dual Battery System arrangement so the equipment never flattens the battery that starts the engine. Departments also fit the vehicles out to a common specification so that any officer can step into any cruiser in the fleet and find the switches, radio, and computer in the same places, which matters when seconds count during a response.