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Los Angeles County Sheriff Tests Police Vehicles
Each year since 1974, the Los Angeles County Sheriff’s Department has conducted performance and fuel economy tests on police vehicles. With a total square mileage about the size of the state of Connecticut, Los Angeles County offers widely diverse operating conditions ranging from traffic-clogged urban streets, winding mountainous roadways, scorching deserts and high-speed freeways.
In comparison with the annual vehicle tests performed by the Michigan State Police, the Los Angeles Sheriff testing program places less emphasis on top speed and high-speed handling, and places more attention on urban handling and braking issues, and on mechanical reliability issues.
While this LASD program dates back to the 1970s, when they took it over from the Los Angeles Police Department, the LAPD began police vehicle testing in 1956! The current testing actually involves both the LASD and the LAPD. Both agencies supply EVOC driving instructors to help evaluate the vehicles.
Preliminary Handling Test
All vehicles, regardless if they are Police Package (pursuit-certified) or Special Service Package, must undergo the Preliminary Handling Test. This is a 1.57-mile high-speed driving course laid out at the Los Angeles County Fairgrounds “Fairplex” Complex. Each vehicle is driven eight laps by each test driver. Four test drivers are used for each vehicle, for a total of 32 laps. The speeds on this high-speed course average between 62 and 70 mph.
The laps are timed by utilizing a Hot Lap digital-infrared timing device mounted inside the vehicle. Both the fastest and slowest laps are automatically eliminated and the remaining six laps are averaged. Each driver also subjectively evaluates each vehicle at the end of this phase. Vehicles that are rated as “unacceptable” are disqualified and are not allowed to participate in further testing.
The fastest police vehicle during the Preliminary Handling Test was the 5.7L Dodge Magnum followed closely by the 5.7L Dodge Charger. These two were about 14 car-lengths ahead of the next closest vehicles, the Ford CVPI (3.27), Ford CVPI (3.55) and 3.5L Dodge Charger, which were all within ½ second of one another.
Immediately after the Preliminary Handling Test, the brakes are tested. This simulates actual operating conditions within police service, such as after an emergency run or pursuit situation. This timing also makes this brake test the hardest, most severe brake test performed by the police community. All of the brake testing was conducted in the same area of a smooth portion of the asphalt track surface, thus maintaining the same coefficient of friction during the testing.
The test vehicle is accelerated up to a speed of 80 mph, and the brakes are applied to maintain a deceleration rate of 22 fps2 without ABS activation. This test is repeated three additional times. The vehicle is allowed to sit stationary for five minutes, allowing the brakes to cool down.
After the cool-down, the vehicle is accelerated to a speed of 60 mph and is decelerated at a maximum rate, just short of Antilock Brake System (ABS) activation. This procedure is repeated two additional times. After a two-minute cool-down period, the vehicle again is accelerated to 60 mph and the vehicle is stopped to simulate a “panic-stop” with ABS activation.
Any malfunctions (fade or pulling) are investigated to determine the cause. If the cause is correctable, then the vehicle is allowed to be repaired and retested. If it appears that the defect is a result of engineering or design, then the vehicle is disqualified from further testing.
The police sedan with the best brakes was the Ford CVPI (3.55) with a 131.8-foot average stopping distance. However, this result must be balanced with the 159.2-foot stopping distance from the virtually identical Ford CVPI (3.27). The Dodge Charger and Dodge Magnum, in both powertrains, were close behind the Ford CVPI (3.55).
A Datron Speed Sensor, driven by a laptop computer, records acceleration times at all speeds up to 100 mph. Standing-start, ¼-mile acceleration is also measured. Maximum top speeds are not attempted.
The police sedan with the fastest acceleration to 60 mph and to 100 mph was the 5.7L Dodge Charger with times of 6.5 seconds and 15.1 seconds, respectively. It was also the fastest sedan in the ¼-mile with a time of 14.9 seconds at a speed of 99 mph. The 5.7L Dodge Magnum was close behind with almost identical times.
The next fastest accelerating vehicle was the 4.6L 3-valve Ford Explorer SUV, taking just 7.8 seconds to reach 60 mph. Both the Ford CVPI (3.27) and the Chevy Impala hit 60 mph in 8.4 seconds. All the rest of the test vehicles took between 8.4 and 8.9 seconds to reach 60 mph.
The final test of pursuit vehicles is the Pursuit Course. This is limited to vehicles that are rated as Police Package (pursuit-certified) by the vehicle’s manufacturers. Special Service package vehicles are not tested in this phase. This is a 2.45-mile course that simulates a pursuit situation within an urban environment, consisting of a maze of twisting right and left-hand turns, along with obstacles littering the roadway. The speeds on the city street simulation course average between 31 and 35 mph.
Two test drivers are used to evaluate each vehicle and times are recorded on the “Hot Lap” recording device mounted in the vehicle. Each driver completes two laps around this course. A vehicle is deemed unacceptable, if it cannot complete the four-lap course in less than a combined time of 4 minutes, 45 seconds. Prior to participating in the Pursuit Course, at their option, the vehicle representatives were given the opportunity to rebuild the brake systems.
The fastest sedan on this phase was the 5.7L Dodge Charger, with a four-car-length lead over the next cluster of cars. In this cluster were the 3.5L Charger, the Ford CVPI (3.55) and the 5.7L Dodge Magnum, all within 1.5 car-lengths of one another. All test vehicles met the LASD maximum lap time requirement.
Due to the large number of vehicles tested this year, the testing process took two days. During these two days, there were wide temperature variations between the morning and afternoon. For example, the Ford CVPI with 3.27 rear gears was run at temperatures around 68 degrees F, while the Ford CVPI with 3.55 rear gears was run at temperatures around 86 degrees F. This may partially explain the seeming better acceleration from the 3.27 geared car. The 3.5L Dodge Charger was tested at temperatures around 78 degrees F, while the 5.7L Charger ran under 92 degrees F conditions.
Fuel Efficiency Test
The Fuel Efficiency Test simulates real-world conditions and is conducted over a 100-mile course. Each car is run through this course twice, with different drivers. Test results are then averaged between the results that each driver obtains. The course is divided equally with urban, suburban and freeway driving conditions. The vehicle’s headlights and air conditioning are turned on and the transmissions are placed in the “Overdrive” position.
The vehicles are driven in a normal manner, i.e., the vehicles are neither driven gently nor driven for maximum performance. By definition, this test simulates the mileage that a detective or administrative vehicle would obtain. Experience shows that a marked patrol unit would obtain about 60 to 70% of these mileage figures.
The police sedan with the best gas mileage under these test conditions was the 3.9L Chevy Impala with a 24.7 mpg average. The 3.5L Dodge Charger was close behind with a 24.1 mpg average. No other vehicle got better than 20 mpg. The Ford CVPI (3.55) averaged 16.8 mpg.
Heat Rise Test
In the early 1970s, the LASD became very concerned with excessive operating temperatures, which were a result of the early exhaust emission controls. California vehicles manufactured after 1972 were especially affected as they ran hotter than the other 49 state vehicles as a result of mandated oxides of nitrogen controls. At that time there were no emissions exemptions for emergency vehicles. It wasn’t until 1982 when the standards were changed and emergency vehicles only had to meet federal emission standards and not the stricter California standards.
In addition to decreased performance, excess heat can potentially damage the engine, power steering and transmission—thus could shorten the service life of these vital components. Beginning in 1974, the LASD incorporated heat testing of various components as part of the testing process.
Following completion of the 32-lap Preliminary Handling Evaluation, temperature sensing probes measure the fluid temperatures of the engine coolant and oil as well as the transmission and power steering fluids. The ambient temperature of the outside air in direct sunlight is also measured and factored into the vehicle measurements. Recorded temperatures are then compared against what the manufacturers recommend as maximum temperatures. This is a pass/fail test and a failure at this point will disqualify a vehicle.
Vehicles of the early 1970s would generally operate at a coolant temperature of 180 degrees, and temperatures in excess of 200 degrees were considered overheating. Today’s cars now run safely between 200 and 260 degrees, and the higher operating temperatures bring about improved fuel efficiency and lowered emissions.
Other improvements include long-life coolant and vast improvements in coolant hose technology, which improve engine reliability against the destructive damage of overheating. We are now seeing longer engine and transmission life due to this technology, which translates into longer projected lifecycles.
This brings about the controversy of silicone coolant hoses, which came out in the 1970s to combat what was believed to be deterioration of the hoses due to ozone from polluted air and excessive underhood heat. Further studies showed that the true problem was the combination of coolant coursing through the various metals in the engine, i.e., aluminum, copper, iron and steel. The reinforcing fabric in the hoses wasn’t up to the task of dealing with the chemical reactions of these combinations.
The auto engineers then went to EPDM-ECR (Ethlyene-Propylene-Diene rubber—Electro-Chemical Resistant) hose material, which is projected to last the lifetime of the vehicle. While the black EPDM-ECR hoses have been standard since on the Crown Victoria since 1994, silicone hoses are still an (unnecessary) $320 option.
All of the vehicles easily passed the fluid heat-rise tests. No powertrain was even close to the maximum temperatures of coolant (260 degrees F), engine oil (300 degrees F), trans oil (275 degrees F) and P/S fluid (275 degrees F).
The vehicles were tested with the Original Equipment (OE) factory tires. The tire testing for construction, design, wear patterns, durability and handling ability is run concurrently with the other tests. Simply put, the OE tires must successfully complete 32 laps of the 1.57-mile high-speed road course, two laps of the 2.45-mile city pursuit course, and complete the Brake Test. All OE tires passed this test phase.
The LASD rates space utilization and human factors in an evaluation conducted by several uniformed deputies. The evaluations are conducted separately and the ratings are averaged to minimize any individual prejudices for or against any of the vehicles. Vehicles are evaluated for general suitability and efficiency as a patrol vehicle, or other specific functions that the LASD may require.
Mechanics that service the department’s vehicles also evaluate each vehicle for ease of routine maintenance and service as well as the ease of repair of various vehicle components.
Finally, the ease of installation of communications equipment (two-way radios and Mobile Data Computers) is rated. The radiated output of this equipment must not interfere with the operation or performance of the vehicle, nor may the vehicle cause excessive radio interference. Technicians from the Los Angeles County Sheriff’s Department Communications and Fleet Management Bureau conduct this evaluation.
Drivers noted the Impala had a slight amount of understeer and brake fade, while one driver commenting that the 2006 Impala was the best Impala ever. The larger 3.9L engine for 2006 made the Impala a full second quicker to 60 mph compared to last year’s car. The zero to 100 mph times are six seconds quicker. Top speed is speed limited at 142 mph, yet fuel consumption is improved by 5%.
On the Tahoe, drivers commented on power-induced oversteer, which they felt was predictable and manageable. The Tahoe, being higher centered than a sedan, has tires engineered to slide, rather than grip and cause more body roll. Drivers commented that this vehicle had a slight to moderate amount of body lean and bounce during the turns. Some brake fade was noted, however the brakes were consistent. The drivers and evaluators gave the Tahoe high praise for driver comfort, i.e., leg room, visibility and ease of reaching controls.
Both the 5.7L Hemi® powered Charger and Magnum scorched the track with six-second acceleration times to 60 mph and many car-length advantages over the other vehicles on the road courses. The performance of the Hemi® cars was described by one driver as “simply awesome.” Ditto the brakes, which were described as “in a league of their own.” The drivers felt the performance of the 3.5L V-6 versions of the Charger and Magnum was similar to that of the Ford CVPI and Chevrolet Impala.
The Ford CVPI got high marks for handling, power range and shift-points. The drivers noted only a minimal amount of bounce and lean. They did notice some brake fade toward the latter portion of the Preliminary Handling Test; however, the fade was minimal with the brakes slowing the car at an acceptable rate of deceleration. While 60 mph acceleration was similar to previous year models, the acceleration to 100 mph was improved over last year’s models.
On the Ford Expedition, the driving instructors commented that handling was predictable and manageable, and that the big SUV had great brakes.
An Explorer was submitted for testing as a Special Service vehicle; however, Ford pulled the SUV from further testing after the Preliminary Handling Evaluation. The 2006 Explorer comes standard with AdvanceTrac and Roll Stability Control. The Advance Trac (traction control) light kept coming on, which is normal for the system given this kind of aggressive driving. Ford believes the SUVs, as a class, are not suitable for pursuit driving because of the higher center of gravity. The AdvanceTrac system is designed to minimize that occurrence, but the LASD test obviously will push the system to the limit.
While the Los Angeles County Sheriff’s Department does not recommend any specific vehicle(s) or tire(s), their test results are published annually.
For further information on the program, contact:
Los Angeles County Sheriff’s Department
Communications and Fleet Management Bureau
1104 N. Eastern Avenue Door #50
Los Angeles, CA 90063
John Bellah is the technical editor of Police Fleet Manger and corporal with the California State University, Long Beach Police. He may be reached via e-mail at email@example.com.
Published in Police Fleet Manager, Mar/Apr 2006
Rating : 8.0
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