Background
On July 1, 1996 the three biggest cities in Sweden introduced “Environmental Zones” in the city centers. The main purpose was to prohibit the use of old and highly polluting Heavy Duty Vehicles in the town centers thereby improving the ambient air quality. The program targeted highway truck and bus engines.
Effective January 1, 1999 a similar program is introduced by the cities to reduce emissions from Off-Road Engines. The program is applicable for a variety of applications, ranging from construction machines, wheel tractors, and excavators to lawn movers and hedge cutters.
A significant part of the construction work carried out within city limits is performed under the responsibility of the local municipality. In those cases the contractor has to meet certain environmental requirements to be eligible to bid for a municipal contract. The contractor has to either use only new engines that meet the latest emission requirements, or to retrofit older engines with a certified emission control device. Emission control devices used under the program can be either oxidation catalytic converters or oxidation catalytic converters in combination with particulate filters.
If several contractors are bidding for the same assignment, the contractor with the most modern engines/machines will win, even at a higher cost. To a certain extent, the municipalities are prepared to pay extra money for reducing emissions in the city area.
Emission Requirements
The following are the base emission requirements:
- Highway Heavy Duty Vehicles, e.g. transport trucks used during the construction work, shall fulfill the requirements of the “Environmental Zones” program.
- Diesel fueled engines used in all remaining "Off-Road" applications shall fulfill at least EU Stage 1 / USA Tier 1 standards for off-road engines.
- Gasoline fueled engines shall fulfill the US Tier 1 or California requirements.
Diesel engines not fulfilling the base requirements (EU/USA Stage 1/Tier 1) must be equipped with a certified catalytic converter. For certain applications, expressed as a list of the most polluting machines, particulate filter must be installed in addition to the catalytic converter.
Diesel engines that fulfill the base requirements must be equipped with after-treatment devices at the time they reach 8 years of age. The maximum allowed age of an engine that is equipped with a catalytic converter is 14 years. The maximum allowed age of an engine that is equipped with a catalytic converter/diesel particulate trap combination is 16 years.
For gasoline fueled engines not fulfilling the base requirements certain age limitations apply in combination with the requirement that the engine must be equipped with a catalytic converter. Hand held machines must be not older than three years. Other engines must be not older than five years.
In addition to the emission requirements, contractors must meet the following conditions:
- 10% of the fuel used within the contract must be renewable (eff. 2000).
- In general, the best available fuel shall be used.
- Environmentally benign engine lubrication oils are required.
- The content of PAH in the rubber tires must be limited.
- Maintenance and service of the machines must be carried out on a regular basis, according to the manufacturer requirements.
- The noise protection of the machines must be checked and maintained.
Equipment Certification
List of approved off-road aftertreatment devices
Retrofit emission control equipment has to be certified for use under the program. In order to reduce the approval cost, equipment certifications issued under the Environmental Zones program can be transferred for “Off-Road” applications, despite the significant differences in the engine test cycles. Devices to be used under the Environmental Zones program (truck and bus) are tested according to a transient test procedure, while devices for “Off-Road” applications are tested according to steady state test procedures.
The test procedures for approval of devices for “Off-Road” applications are specified by the ISO 8178 standard. Different test cycles apply for different engine categories, in accordance with the standard.
The requirements for approval are listed in the following table.
| Engine | Equipment | Pollutant | Emission Reduction |
|---|---|---|---|
| Diesel | Particle Filter | Diesel Particulate Matter (DPM) | 80% |
| Catalytic Converter | Hydrocarbons (HC) | 80% | |
| Gasoline | Catalytic Converter | Carbon Monoxide (CO) | 50% |
| Hydrocarbons (HC) | 50% |
For all applications, regardless of the engine used, no increase in oxides of nitrogen (NOx) and noise is accepted.
Laboratories accredited for Environmental Zones’ certifications are also responsible for approving the “Off-Road” retrofit devices. The manufacturer of the devices, however, must arrange for a proper installation on the different machines. He is also responsible for the warranty.
The manufacturer of the equipment submits documents to an accredited testing laboratory and applies for an approval of the equipment according to the requirements issued by the cities. The application includes (1) forms supplied by the test laboratory, (2) test results, and (3) requirements for installation of the equipment on the engine/machine. The documents are reviewed and, in most cases, a confirmative test of the equipment is carried out at the accredited laboratory.
The list of certified devices includes catalytic converters and combinations of converters and filters in the power range 5-560 kW from a number of different suppliers.
This article based on information submitted by Lennart Erlandsson, MTC.