Chalmers tekniska högskola Acoustic pass-by measurements of in-service trains

Acoustic pass-by measurements of in-service trains

Chalmers Tekniska Högskola Aktiebolag

Direct award

Request for tender:

Acoustic pass-by measurements of in-service trains

Chalmers Applied Acoustics is carrying out a research project on rolling noise on slab tracks. In this context, a measurement campaign will be carried out in September 2021 at Trafikverkets demonstrator at Gransjö in Northern Sweden, where a new type of slab track is tested. The measurements are financed by Trafikverket. For a part of the measurements tenders are invited here. This includes the measurement of rolling noise and accelerations in the track during pass-by of in-service trains and the measurement of structure-borne and air-borne transfer functions in and at the track. Personnel from Applied Acoustics will be present during the measurements and is available for assistance.

Requirements specifications of goods/services

The purchase must include the following products/commitments/services:

Place:

The measurement location has the address

Trafikplats Gransjö, S-961 92 Boden, Sweden  

On google maps

https://goo.gl/maps/96doS42KDnQQ36pn9

Time:

The measurements are planned for week 37.

Required measurements:

All measurements are carried out both centrally in the 60-m long slab track section and at a reference section with ballasted track in vicinity to the slab track section. The exact location of the reference section will be decided in situ by Chalmers.

1). Pass-by measurements

Pass-by measurements are carried out during one working day for all passing trains (in total 27 trains are normally passing within 24h). However, at least 5 iron ore line trains, 5 other freight trains (Green Cargo) and 5 passenger trains have to be measured. Measurements in both sections have to be carried out for the same passing trains. All measurements within one section have to be synchronized, but they do not have to be synchronized between the two sections. All data has to be delivered as calibrated temporal raw data (sound pressure, acceleration). If further processed data is required in addition, this is specified below.

The following quantities have to be measured during pass-by:

a. Sound pressure at both the slab track and the ballasted track section:

measurement at one side of the track at 7.5 m from the centre line of the track at the heights 1.2 m, 2.0 m, 3.0 m and 3.5 m above track level; in total 8 microphones; measurement according to ISO 3095 Section 6 but with the difference that roughness and TDR measurement are not included in this assignment and that vehicle conditions and train speed are ‘as is’. Required valid frequency range at least 20 Hz – 10 kHz. Data delivered as calibrated temporal raw data (i.e. the sound pressure signal over time). In addition, for each pass-by and microphone position, the A-weighted sound pressure level LpAF(t) as a function of time with time weighting F (fast), the A-weighted equivalent continuous sound pressure level LpAeq,Tp, the pass-by time Tp and the A-weighted sound pressure level as spectrum in one-third octave bands in the range of at least 31.5 Hz to 8 000 Hz are required according to ISO 3095.

b. Vertical and lateral rail acceleration at slab track section:

measurement on the outside of both rails, positions according to EN 15461; vertical and lateral acceleration above a rail seat and mid-span in the middle of a block; in total 8 uniaxial accelerometers; valid frequency range at least 20 Hz – 10 kHz;

c. Vertical Acceleration of block and slab at the slab track section:

measurement of vertical block and slab acceleration on both sides of the track close to a rail seat and in the middle of a block; in total 6 uniaxial accelerometers (2x slab, 4x block); If there is no space on the top of the slab to attach uniaxial accelerometers to measure vertical slab acceleration, two 3-axial accelerometers attached to the side of the block might be required to measure vertical slab acceleration; valid frequency range at least 5 Hz – 3 kHz;

d. Vertical and lateral rail acceleration at ballasted track section:

measurement on the outside of both rails, positions according to EN 15461; vertical and lateral acceleration above sleeper and at midspan; in total 8 uniaxial accelerometers; valid frequency range at least 20 Hz – 10 kHz;

e. Vertical sleeper acceleration at ballasted track section:

measurement of vertical sleeper acceleration next to the rail seats on both sides and in the middle of the sleeper; in total 3 uniaxial accelerometers; valid frequency range at least 5 Hz – 3 kHz;

f. Train speed of each measured train

The positions of accelerometers and microphones are indicated in the attached document measurement_positions_gransjö.pdf.

2) Structure-borne transfer functions

a. Transfer function rail to rail, block, slab and microphones in slab track section:

vertical and lateral excitation on the rail on both sides (8 excitation positions), response using same accelerometers on rail, slab and block and same microphones as used in pass-by measurements (18 responses); 8x18 combinations; valid frequency range at least 20 Hz – 10 kHz for rail-rail, rail-microphones and 5 Hz to 3 kHz for rail-block and rail-slab; data delivered as complex frequency response functions with corresponding coherence and the calibrated temporal raw data

b. Transfer function rail to rail, sleeper and microphones in ballasted track section

vertical and lateral excitation on the rail on both sides (8 excitation positions), response using same accelerometers on rail and sleeper and same microphones as used in pass-by measurements (15 responses); 8x15 combinations; valid frequency range at least 20 Hz – 10 kHz for rail-rail, rail-microphones and 5 Hz to 3 kHz for rail-sleeper; data delivered as complex frequency response functions with corresponding coherence and the calibrated temporal raw data

3) Air-borne transfer functions

Requirements for all air-borne transfer functions: valid frequency range at least 20 Hz – 10 kHz; data delivered as complex frequency response functions with corresponding coherence and the calibrated temporal raw data

a. Acoustical transfer function in slab track section, free track :

measurement from an omnidirectional loudspeaker in a typical wheel center position (in total two excitation positions; one above each rail) to the microphones at one side of the track using the same microphone positions as used in pass-by measurements (4 response positions); The source strength of the loudspeaker needs to be determined (additional microphone at 1m distance from the loudspeaker or measurement of membrane velocity with an accelerometer; A suitable loudspeaker can be provided by Applied Acoustics.

b. Acoustical transfer function in slab track section, at presence of a wagon:

One train will be stopped in the test section. Measurement from an omnidirectional loudspeaker in a typical wheel center position (in total two excitation positions; one above each rail) to the microphones at one side of the track using the same microphone positions as used in pass-by measurements (4 response positions); all other requirements as under 3) a.

c. Acoustical transfer function in ballasted track section, free track:

measured as in slab track section

d. Acoustical transfer function in ballasted track section, at presence of a wagon:

measured as in slab track section.

Further information and requirements:

- Delivery of data as calibrated temporal raw data (and processed data in some cases as specified above) with all necessary information for continued processing, analysis, and evaluation; The delivered data format has to be readable in Matlab.

- Three persons from Chalmers are available for assistance during the measurements (set-up, execution and dismounting). However, the consultant has the full responsibility for execution and quality of the measurements.

- Time to plan the measurements with Chalmers Applied Acoustics before departure and in situ needs to be included in the contract.

- Trafikverket takes care of the security arrangements during the measurements.

- The measurements are planned for week 37. However, as the measurements are  weather dependent (rain, wind, snow), it can become necessary to postpone the measurements with short notice. This must be done in consultation with Chalmers and the measurements must be carried out as close in time to week 37 as possible (week 38 or week 39).

- Maximum price 135 000 SEK. This price includes all costs of the assignment including costs caused by rescheduling the measurements due to bad weather as described above.  

Price

Price shall be submitted in SEK excluding VAT and include all related costs requested in this request for tender.

Agreement terms

The supplier must accept all agreement terms.

Tender submission

The tender must be received no later than 2021-08-01.

The tender shall be valid until 2021-10-01.

Questions during the tender period

Questions should only be asked via the function "Questions and answers" in Mercell Direct Procurement.

OBSERVE:  Due to holiday times, last day for questions will be 2021-07-19. Questions will be answered 6 days before the last day for tender.

Evaluation of tenders

The most economically advantageous tender (i.e. an assessment of price, quality, service etc.) will be chosen.

Description of the criteria that will be assessed (in the prioritized order):

1. Competence and capability to carry out pass-by measurements according to ISO 3095, measurement of accelerations at the railway track and measurement of structure-borne and air-borne transfer functions at the railway track as specified in this document. Competence and capability must be demonstrated by providing the educational background and a CV of the person(s) that will carry out the measurements and by demonstrating previous experience with such measurements (describe your previous experience with such measurements and provide three reference projects with contact details of corresponding reference persons)

2. Competence and capability to cooperate with academia in the planning and execution of measurements demonstrated with references.

3. Price.

It is a reference group at Architecture and Civil Engineering, division of Applied Acoustics, that will evaluate the required competence.

Confidentiality and the freedom of information principle

After the procurement has been terminated the principle of public access to official records applies. This means that all documents related to the procurement process become public and may be disclosed to anyone who requests access to them. Exceptions may only be made if there is any specific reason to believe that the Tenderer may suffer damage if the information is disclosed.

If you have information that you feel is of such nature, your tender shall include precise details of which information should remain confidential, and how you would suffer damage in case of the public disclosure of this information. Chalmers will evaluate your request and determine whether confidentiality in accordance with Swedish law may be deemed to apply.

Sista anbudsdag
Avbruten

(2021-08-01)

Förfarande

Direktupphandling

Publicerad

2021-07-05

Dokumenttyp

Direktupphandling

Leveransorter

Västra Götalands län

Diarie-/referensnummer

ACE 2021-0174