Page images
PDF
EPUB

TESTS AND ADJUSTMENTS: S1.08 (Cont'd)

(1) Noise Tesis

I.

Test Conditions: Conformance with the specifications is to be based on measurements taken in essentially a free-field environment such as outdoors, away from any reflecting surfaces other than the ground on which the car is resting, except for transmission loss measuremenis. All measurements shall be made at locations where reflected sound, such as reflections from nearby walls, floor or other equipment, will not iniiuence the directly radiated sound from the equipment measured by more than 2 dB. All measurements shall be made with an ambient sound level in the vicinity of the test measurement loatics of not less than 10 dB below the noise produced by the equipment being measured, when evaluated using the same weightingor octave band. Where auxiliary methods of driving or loading equipment such as motors or dynamometers, are required, these devices shall be temporarily enclosed or baffled to eliminate their effect on the equipment noise being measured. For equipment noise measurements with the car stationary or on jacks, the car shall be located outdoors on a ballast-and-tie, at-gade trackbed in an area. free of barriers, third rail coverboards, or oiher sources of interference. Car body section transmission loss measurements may be performed outdoors or indoors. Car interior and exterior noise level tests with the car moving shall be done at a section of clean, smooth rail on a ballast-and-tie at-grade track with no sound barriers or third rail coverboard on the measurement side.

2. Equipment Noise Tesi Procedures: Using sound level mater and analysis equipment as

specified in $16.01, the Contractor shall measure the Sound Level produced by equipment in the operating mode at the distances and directions specified and using the scales and frequency ranges specified in S16.02.

3.

In-Vehicle Noise Test Procedures: Using sound level meter and analysis equipment as specified in S16.01, the Contractor shall measure the Sound levels inside the vehicle with all equipment energized and all components operating except the propulsion motors, shall measure the noise levels inside the vehicle with each individual equipment system energized, ard.shall measure the sound levels inside with the vehicle moving at speeds up to 70 mph on ballast-and-tie at-rade track. The sound readings shall be obtained at sufficient locations in the ar to determine that the noise level limiis are not exceeded at any point in the passenger space.

4.

Tests of First A Car and B-Car Sets of Equipment: Noise level measwerents shall be performed on the first car sets of equipment before and after installation on the car io verify that the noise generated is within the limits indicated in S16.02. The tests shall include measurements to deier mine the noise levels produced by the traction motors ar.d propulsion system gearing for one car and the noise levels produced by the compressor, motors, blowers and other noise generating components of the firsi tivo cars.

5.

Tests of Firsi Complered A Car and B-Car: Noise level and transmission loss tests shall be performed on the first completed car to verify performance within the limits indicated in S16.02 (e), (1), ard (g). Noise level tests shall be performed on the first completed Awrand B-car to verify performance within the lirits indicated in S16.02 (b), (c), (d), and (h). Tiese tests shall include mr.easurements to determine the exterior noise levels from the vehicle equipmeni ard the complete vehicle both stopped and inoving, ihe car interior noise levels from the vehicle equipment and with the car moving, and the transmission loss of the vehicle body sections.

[blocks in formation]

TESTS AND ADJUSTMENTS: S1.08 (Contd

6.

Vehicle Body Transmission Loss: The supplier shall, using the procedures outlined in AST. E336-677, Tentative Recommended Practice for Measurement of Airborne Sound Insulatio in Buildings, perform tests to detetmine the sound transmission loss of the vehicle bod sections. Evaluation of the sound transmission loss of each characteristic Section of th completed car body shall be done using one or a combination of the following procedures:

1. With the car located outdoors on baila stand-tie, at-grade trackeed or indoors in a spaa

where reflected sound from nearby walls or floors will not influence the sound sa diate from the car body by more than 2d3, the Contractor shall, using portable loudspeakers in manner approved by the engineer, create a random noise of constant level, for th frequency range encompassing the 250 Hz to 2000 Hz center frequency octave bands, wit sufficient Sound pressure Level inside the car that the noise transmitted through the ca body is a least 10 dB higher than the outside ambient SPL in each octave band and wit: sufficient diffusion or distribution that the sound level in the car is uniform within 3 dB a 12 inches or more from any body surface. (Achieving a uniform sound field over the ca floor will require removal of the seats.) Using this procedure the car body section soun insulation can be evaluated by using a sound level meter and octave band analyzett measure the space average SPL inside the car in the 250, 500, 1000 and 2000 Hz cente frequency octave bands and by also measuring the exterior SPL for each of these octay bends at a distance of 12 inches from all car surfacs at a sufficient number of locations t determine the average noise reduction for each characteristic body section, such as th floor, walls, roof and doors. The measurements must include the influence of any soun: leakage such as at ducts, seals or openings and the influence of flanking sound transmissio paths at locations such as the floor/wall juncture. The difference between the interior spac average Sound Pressure Level and the average exterior Sound Pressure Level at each sectio. is the Noise Reduction provided by the car body sections. Noise Reduction measured i this manner is 6 dB greater than the transmission loss. The measurements must be correcte to transmission loss in accordance with procedures given in ASTM 336-67T in order to determine compliance with the specified minimum sound insulation of each car body section.

2. With the car located near highly reflective surfaces, such as over a maintenance and

inspection pit, the trarsmission loss may be measured in accordance with the two-roor reverberant sound field methods indicated in ASTM 336-6TT. To create a satisfactor reverberant condition outside the car, and to define the boundaries of the space, ter.porar, bafiles or barriers approved by the engineer shall be placed between the car body exteric and the reflecting surfaces, such as between the car body exterior walls at the floor leve and the edges of a maintenance pit, to define a closed space beneath the car for testing th car floor transmission loss. The tertiporary baffles both define the space exterior to the ca and prevent flanking paths outside the car from influencing the measurements, for example by preventing sound transmittei ihrough the car walls or doors from bypassing the floo during a test of the floor.

Addendwn No. 7

1-29

Submission #2

November 24, 1975 Request

GAO HEARING

QUESTION 11

In the May 8th report to Senator Byrd the GAO identified possible

increases and decreases on various route realignment possibilities.

Please provide a description of the current status of these routes and

your latest estimates of the possible cost consequences of the various

locations possibilities now under consideration.

GAO's May 8th report to Senator Byrd addressed possible adjustments

to the Authority's November 1974 capital cost estimate of $4,453.7 million

due to probable realignments of six routes (B, E, F, H, J and K).

At this

time, the alignments for Routes B, E and F are still questionable.

Routes

J and H were the subject of a resolution adopted by the Authority's Board

of Directors on December 4, 1975.

The location of the K Route in the

median of a highway along the 1-6ó corridor is still a possibility. The

current status of the six routes discussed in the GAO report

is detailed

below:

B ROUTE

The ARS Glenmont Route between the Silver Spring and the Glenront

Stations was planned to be constructed in earth tunnel.

However, the

accrued geologic data indicated that the quality of soil was not suitable

for tunneling.

A nuber of alternatives were developed of which two were

considered to be feasible.

One was Scheme A-l which varied from the ARS

plan in tuo respects.

The running lines were placed lorer in rock suit

able for tunneling and the stations were placed higher to permit cut-and

cover construction.

The second alternative, Scheme B was similar to the

ARS in that both lira and stations were to be tunneled but the profile was

Towered to avoid the weathered and fractured rock characteristic of the

ARS profile.

Coordination with the local government and the public has

-2

QUESTION 11 (Continued)

revealed their interest in a combination of alternatives, i.e., deep tunnel

construction for all the line and the Forest Glen Station; the Wheaton

Station
Station and Glencon:hould be constructed by cut-and-cover method.

The Glenmont Storage Yard has also been a great concern to the residents

in the proximity of the yard site.

Their concern has been reconciled through

an extensive degree of community and local governgeni coordination.

A

number of revisions are being considered for the purpose mitigating the

impact of the yard on the community.

The revisions include enclosing

the lead tracks, eliminating the loop tracks and contouring the earth

to attenuate yard noises.

If a combination of the A-1 and B alternatives is chosen by Montgomery

County and adopted by the Authority's Board of Directors, the increase in

cost may be considered an add-on funded by the County, as determined by the

Board.

E ROUTE

Several different alignments have been considered for the E Route within

the District of Columbia.

Between Columbia Heights and Fort Toiten Stations

the Alternative c alignment has been widely regarded as the most desirable

alignment.

Outbouns of Columbia Heights the Alternative c alignment separates

the running lines, the cutbound on Park Road, the inbound on Monroe Street.

The lines nerge inco:nd of Georgia Avenue and follow New Hampshire Avenue

to Rock Creek Cezotery.

The alignment crosses under Rock Creek Cenetery

and continues to the Fort Totten Station.

The running lines are planned

to be constructed in earth tunnels while the stations will be constructed

by cut-and-cover, except for Fort Totten Station which is in retained cut.

Outbound of tre fort Totten Siation some 2000 feet of the line is on

the surface and aerial structure.

Thereafter, it is subsurface in a twin

-3

QUESTION 11 (Continued)

cell box to be constructed by cut-and-cover.

There is community opposition to the line in New Hampshire Avenue and

to the surface/aerial line in Fort Totten Park.

Also Rock Creek Cemetery

officials oppose the proposed tunnel across their property and have voured

to litigate.

If this alignment is chosen for the Districi of Columbia,

there will be an increase of $12.0 million over the cose of the ARS align

ment which may be considered an add-on funded by the District as determined

by the Board.

The portion of the Greenbelt Route in Prince Georges County recommended

by the Authority's staff, after crossing the District line at grade, proceeds

in subway in an easterly direction south of Carroll Manor and under Avondale

Road. The alignment then turns to the northeast to the aerial Chillum Station near the Queens Chapel Drive in Theatre. it' then proceeds in earth tunnel

under Queens Chapel Road to the intersection of Oliver Road and Queens Chapel

Road before turning north to the at grade Prince Georges Plaza Station.

The

alignment continues in earth tunnel under Adelphi Road before turning into the

median of University Boulevard to the retained cut University Boulevard Station

located at Stadium Drive.

The E Route then crosses over Stadium Drive and the

southbound lane of University Boulevard before continuing in subway under the

golf course.

It then continues in subirey under Metzerott Road before swinging

to the west of the PEPCO right-of-way and proceeding to the terminal station in

the 1-95 and 1-495 interchange.

The service and inspection yard is located north

of 1-495 between the north and south bound lanes of 1-95.

This aligndent if approved by Prince Georges County and adopted by the

Authority's Board of Directors would exceed the programmed cost for the Prince

Georges County segment of the Greenbelt Route by $117 million.

Any cost over

the $228 million programned amount will be considered an add-on totally funded

by the County.

« PreviousContinue »