Reduction of vehicle noise emissions – Technological potential and impacts
Proposed EU regulation on vehicle noiseIn December 2011 the European Commission published a draft EU Regulation for the sound level of motor vehicles. This draft Regulation introduces a new test method for measurement of the noise emission of road vehicles as part of the type approval procedure, which is intended to be more representative of the actual conditions in normal urban traffic than the old test method. Furthermore, the draft Regulation proposes more stringent limit values for noise emission than the values currently in force. The proposal is largely based on the VENOLIVA study, executed by TNO between November 2009 and March 2011.
At the request of European Federation for Transport and Environment and the Dutch Ministry of Infrastructure and Environment, TNO has performed a new analysis on the impact of the Phase 2/3 vehicle noise limits, as proposed in the draft Regulation. Also the feasibility and impact of a more stringent Phase 4/5 of limit value reductions was assessed. Technical options, appropriate vehicle noise classes with respect to today’s vehicle fleet, industry costs and societal and health benefits have been analysed. New available information has been taken into account based on recent publications, industry consultation, comparison of different valuation methods and comments from various stakeholders. The proposed limit reductions are found to be technically achievable.
An alternative proposal for lower noise limits including an additional step
A new proposal is made for lower limits in the report, adopting the limit values of the Phases 1 and 2/3 of the EC proposal, but recommending a tighter time schedule for implementation. Also the definitions of vehicle sub-categories have been revised, following some of the suggestions from other stakeholders, and two additional Phases, 4 and 5, for further reduction and consolidation of the limit values beyond the EC proposals have been included.
Impact of proposed limit value reductions
Both Phase 2/3 and Phase 4/5 limit values are found to be highly cost effective over the appraisal period 2010-2030. For Phase 2/3 limits, the Benefit to Cost Ratio is 39 (previously 11,4) and for Phase 4/5, 32. Benefits of Phase 4/5 are 326 billion Euro over the appraisal period and the costs are 10 billion Euro. The environmental impact of both phases is substantial. The Phase 2/3 noise limits result on average in 3,1 dB reduction in LDEN traffic noise levels, 25% less highly annoyed people and 15% less highly sleep disturbed people. The Phase 4/5 limits would result on average in 5,2 dB reduction in LDEN levels, 39% less highly annoyed people and 29% less highly sleep disturbed people.
Besides the EC proposal, Germany, ACEA and Japan have made proposals on vehicle subcategorisation, limit values and the time frames of the introduction of the various phases of the limit value reduction. The overall conclusion is that the alternatives are generally significantly less ambitious than the EC proposal and are scheduled much later, delaying the reduction in traffic noise far too long.
In alternative proposals from ACEA, Germany and Japan, modified definitions of vehicle sub-categories were proposed, whilst the EC proposal is based on the same sub-categories as the current limit value system. Therefore the subcategorisation was reconsidered. As a result modified definitions are now proposed for the vehicle categories M2 (medium size buses), M3 (heavy buses), N1 (vans and light trucks) and N3 (heavy trucks). The suggested introduction of an additional sub-category for passenger cars is not recommended.
Technological potential for noise reduction of trucks
For Phase 2/3 limits for trucks, technology is commercially available for shielding and encapsulation, which is applicable without significant R&D effort. Also the additional reductions in Phase 4/5 are feasible, based on available technical solutions that have already been applied in passenger cars and engine test bench experiments. An additional cost of 250 Euro per dB noise reduction per vehicle is estimated for both Phase 2/3 and Phase 4/5, which is around 0,5 % of the vehicle price. This extra cost is passed on to the customer. For Phase 4/5 limits the additional costs for truck manufacturers are mainly due to additional R&D and tooling effort. As key challenges such as thermal management need to be addressed, the impact on the truck design and production will be larger than for the first limit value reduction.
Further reduction of tyre noise
Additional reduction of rolling noise of tyres for all vehicle types will be necessary to achieve a further overall reduction of vehicle noise emission with 2 dB(A) as proposed in Phase 4/5. In order to maintain the balance between rolling noise and powertrain noise, an estimated reduction of rolling noise by at least 3 dB(A) will be required. Therefore a further improvement of the tyre noise Regulation with lower limit values for rolling noise will be necessary to enable the proposed limit values for Phase 4/5.