E-ilf-b-c11-arc-spc-0002 R03
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- 14.2.2Other utility rooms in passenger zones
- 15power characteristics
14.2Acoustic protection14.2.1PlatformAcoustic conditions on the platforms are formed under the influence of noise sources connected with train traffic, Metro technical equipment functioning (mainly ventilation) as well as the presence and behaviour of passengers. In Polish regulations specific acoustic requirements concerning passenger service objects, Metro station, train station, or any similar objects have not been given. Permissible noise level and appropriate reverberation conditions in objects of this type shall be specified individually providing adequate protection against noise, clarity of messages and voice alarm system requirements fulfilment. Lowering the noise level is also a question of comfort and the acoustic quality of an object. The scope of acoustic issues should include:
Noise produced by train traffic The basic document on rolling stock noise TSI, Commission Decision of 23 December 2005 concerning the technical specification for interoperability relating to the subsystem “rolling stock – noise” of the trans-European conventional rail system; that specifies the permissible values of noise level of a passing train and permissible noise level for train drivers, apply to a conventional trans-European rail system and does not apply to Metro. The standard PN-EN ISO 3381 Railway. Acoustics. Measurements of noise inside railbound vehicles specifies the method and conditions of noise measurements and is basically intended for type testing and test measurements, applies to all types of railborne vehicles but does not specify any required values. The standard PN-92/K11000 Rolling stock, Noise. General requirements and tests; in reference to measurement methods corresponds to the standard PN-EN ISO 3381, and as a matter of fact to the previous standard ISO 3095-75, to which the requirements were added. It applies to type testing and test measurements. The noise level recommended by the standard applies to open space, thus it does not apply to Metro (on the stop, the permissible “A” level of acoustic pressure value emitted outside in the distance of 7.5 m in open space is not more than 80 dB). The standard specifies measurement conditions for noise produced by trains passing through and leaving the station, the measurements within underground stations are included, but the standard does not specify any permissible values in this case. The above-mentioned documents concerning railway noise do not include the discussed situation. Acoustic conditions on the platform in normal operating conditions are time variable, thus we can distinguish the phase of expectation for the train, train entry, train stop and train departure. The model time course of the noise level recorded on one of the Metro Warsaw line I stations during entry and departure of a French train has been showed in the Figure 2. The measurements were performed in normal operating conditions during late evening hours in the presence of a minimal number of passengers on the platform, such conditions are most favourable for noise propagation. The measurements were performed in the distance of 3 m from the center line of track at 1.6 m height, with the microphone directed towards the noise source. The recorded sequence included the phase of train entry, door opening, door closing and departure. On the basis of the recorded data the equivalent “A” sound level, exposition "L" level AE and the maximum values have been specified. The first phase marked in the Figure 2 includes the train entry (LAeq = 81,3 dB), the second phase is the train stop time (LAeq = 71,6 dB), and the third is the departure (LAeq = 82,7 dB). Momentary maximum values are 86.9 dB, 76.8 dB and 91 dB respectively.
Fig. 2. Noise level on the platform during the entry, stop and departure of the train. Noise exposure degree evaluation criterion in relation to hearing protection is specified inthe Decree of the Minister of Labour and Social Policy issued on November 29, 2002 concerning the highest admissible concentration and intensity of factors harmful to health in the work environment (Journal of Laws no. 217, pos. 1833). The permissible values given in this document apply to the exposure to noise in workstations, but considering the issue of noise harmfulness, due to the lack of other criterion, this one may be applied also when the evaluation of the Metro passengers noise exposure degree is performed. Permissible noise exposure level on account of to hearing protection in relation to 8-hour day period is LEX,8h = 85 dB. In the discussed example the noise exposure level is described by the formula: LEX,8h = LAE + 10log(1/T) + 10log(n) LAE – noise exposure level during a single stay on the platform T – reference time, s n – number of stays on the platform during the reference time Assuming the averages of exposure level LAE established on the basis of noise measurements performed on the platforms of existing metro stations, the noise exposure level of the passengers staying on the platform has been calculated. During the stay on the platform, expecting the train and leaving the station, the noise exposure level does not exceed approx. LEX,8h = 65 dB, thus it is much lower than the permissible value established on account of hearing protection. Short-duration noise level during train entry is also much lower than the permissible maximum value of A sound level of 115 dB (in practice short-duration maximum level does not usually exceed 93dB). On the platform of C11 station architectural and structural solutions limiting the noise level produced by train traffic will be applied. Sound absorbing ceiling will be applied over the platform. In the bottom part of the behind-track area wall and within the under platform area as well as within the tunnels ends the sound absorbing lining will be applied. The final selection of sound-absorbing elements should take into account the MCD indications and the noise spectrums recorded in the station during train entry (Fig. 3).
Fig. 3. Noise spectrum on the platform during train entry In order to limit formation and spreading of vibrations and material sounds, the trackbed will be founded through vibration isolation components. At least two levels of vibration isolation will be applied.
In normal operating conditions two variants of Metro main fan house functioning will be possible. In the first variant the ventilation is performed in a natural way without the use of fans. Air flow is forced by the movement of trains in the tunnel as it is in case of a piston. In this variant the problem of noise produced by the main fan house does not occur because the fans does not work. In the second variant the air circulation will be forced by the fans located in the station fan house. Fans will work with limited capacity in relation to full capacity used only in emergency conditions. In normal operation conditions, in each fan house one fan will work with capacity not exceeding 30% of the maximum capacity (or two fans with efficiency of 15% each). As it results from theoretical relations, the acoustic force level of the axial flow fan working with 30% capacity is 20-25 dB lower than the acoustic force level of the same fan working at the highest rpm. Acoustic protection measures intended for main fan houses will be adapted to such conditions. In operation conditions the overall noise level produced by the main fan house on the platform will not exceed 60-65 dB. At this noise level the clarity of messages and the appropriate comfort of Metro train expectation time will be provided. Assumed permissible noise level stays in conformity with the recommendations of Functional Application Program FAP and MCD concept design. In order to provide the assumed permissible values the appropriate acoustic protection will be applied in fan houses and in inlet chambers and channels on the platform side. The fans will be fitted with slotted acoustic mufflers installed directly on both sides, on air inlet and outlet. Necessary efficiency will be adapted to the type of fans. At the current design stage free space required for mufflers assemblage in the fan houses has been provided. The walls and ceiling within fan house as well as walls and ceilings of chambers, ducts and shafts located between the air intake and exhaust shaft and the Metro tunnel will be fitted with sound-absorbing lining would be made of mineral wool of 100m thickness under perforated metal sheet (30%). Sound-absorbing lining will also be applied at the tunnels ends.
In emergency conditions, in fire hazard situation, the emergency ventilation system will be automatically turned on. At this time all fans work with maximum capacity at highest rpm. Fans noise level is significantly increased in comparison with normal operating conditions. Noise level of the main fan house in emergency conditions must be limited on account of voice alarm system messages clarity. For purposes of design and voice alarm system effectiveness evaluation within the platform, a situation in which there are two trains and the the ventilation system works in emergency mode at the same time, should be assumed. According to the results of measurements performed on the platform, the equivalent noise level produced by a single stopped train is approx. 72 dB, whereas in case of two stopped trains at the same time the level increases to approx. 75 dB. In such situation an efficient permissible noise level value on the platform produced by the main fan house working in alarm mode is 72 dB. Noise level reduction to this value will be provided by acoustic mufflers installed on the fans as well as the system of soundproofed ducts. Total noise level on the platform in situation of two trains stopped and emergency ventilation working may reach approx. 77 dB. For the purpose of designing voice alarm system installation on the platform, an acoustic background level of 77-80 dB should be assumed. The noise level increases significantly at the time of train entry to the station. At this time the momentary maximum "A" sound level may exceed 90 dB. Obtaining appropriate clarity of voice alarm system messages in this period will not be possible due to high acoustic background level. Such assumption has also been made in the MCD concept design. Train entry period in which the noise level on the platform exceeds 75 dB is usually approx. 20 seconds. In this period the clarity of voice alarm system messages will be limited. It should however be borne in mind that the evacuation action will usually begin after the entry of the train to the station. The final selection of acoustic mufflers in main fan houses will follow fans type specification according to main ventilation system working conditions in normal operation and emergency modes. In determining the necessary effectiveness of acoustic mufflers both conditions will be considered, in the operation mode the noise level at the passenger-accessible zone limit will not exceed 60-65 dB, whereas in emergency mode the recommended value for SWS is 72 dB.
Providing appropriate reverberation conditions on the platform is essential on account of utility and security. It allows to obtain appropriate clarity of messages in operating conditions and proper functioning of voice alarm system in emergency conditions. The necessity of considering reverberation conditions in residential buildings, boarding houses and public utility buildings as well as application of appropriate acoustic adaptation results from the Decree of the Minister of Infrastructure issued on April 12, 2002 concerning "the technical conditions the buildings and their surrounding shall comply with", (Journal of Laws 2002, No. 75, pos. 690 as amended (§ 323 p.2.4 and § 326 p.5). Currently in Poland there are no specified requirements concerning this issue, however, a new PN-B-02151 standard sheet design concerning protection against reverberation noise and specifying reverberation time in different types of rooms is being prepared. According to MCD indications, "... sound-absorbing materials and structures of sound absorption corresponding to reverberation time of 1.7s should be applied inside" on the platform. However, the basic condition is to obtain appropriate clarity of voice alarm system messages, and not to obtain specific value of reverberation time. Entire reinforced concrete ceiling will be covered with sound absorbing coating Sonaspray type or equivalent, with sound reduction index of approx. 0,75. Sound absorbing ceiling will be suspended over the platform itself. On the walls behind the tracks in the bottom part under the edge of metropolitan gallery, acoustic structures made of mineral wool covered with perforated sheet metal (30%) will be installed. Similar structures will be made within the under platform area. Moreover, soundproofing of tunnels ends will be applied along a section of approx. 10 m. Soundproofing components will limit the noise level on the platform, affect the acoustic comfort improvement and cause the decrease of living noise connected with the presence of passengers. According to the results of acoustic measurements suggested by MCD, the acoustic ceiling does not provide the possibility of decreasing the reverberation time in the platform concourse to the value close to 1.7 s and does not guarantee the appropriate conditions for efficient working of voice alarm system. From the acoustic point of view, the ceiling requires modification or change. 14.2.2Other utility rooms in passenger zonesThere are general-access utility rooms in the passenger zones, mainly shopping areas. Permissible values of noise level in rooms of this kind situated in public utility buildings is specified by the standard PN-87/B-02151-02 Building acoustics. Protection against noise of premises inside buildings; Permissible values of sound level in premises. Permissible noise level in rooms depends on their intended use, day time and type of noise source. Separate requirements are established to specify the permissible A sound noise level penetrating premises produced by all noise sources altogether and noise produced by technical equipment. Table 1 lists permissibleA sound noise level values that apply to the discussed case.
Table 3. Permissible “A” sound level of noise in premises according to PN-87/B-02151-02 The requirements apply to fully furnished (equipped) premises in accordance with their intended use, with windows and doors closed. As estimating time one should assume the actual period of the premises intended use by a given group of people. The permissible values for technical equipment apply in particular to noise produced by ventilation and air conditioning systems. Ventilation system operating in the utility rooms will be fitted with acoustic mufflers and other necessary noise protection devices. Sound reduction index required values R’A1 of internal walls separating rooms of different function in buildings of public utility are specified by the standard PN–B 02151-3:1999 Building Acoustics. Protection against noise in premises inside buildings. Sound reduction of partitions in buildings and sound reduction of building elements. Requirements. The standard applies to residential buildings, hotels, and other boarding houses and buildings of public utility including administrative buildings. Retail rooms that will be located in the general-access zone have not been included in the standard, in those rooms no requirements directly concerning walls sound reduction have been specified. Required sound reduction results from the possible vicinity of room being a source of noise.
In the case of cubature facilities of design C784 for metro line II, in view of definitions included in the Building Law, Polish Journal of Laws 2006, No. 156, item 1118 in art. 3, par. 1 section 2 and par 3 – they are not classified as buildings, but as facilities. Therefore, the preparation of energy characteristics for tunnels and underground facilities is not required. ILF CONSULTING ENGINEERS Polska Sp. z o. o. Page ILF 2010 Yüklə 296,79 Kb. Dostları ilə paylaş:
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