THE MRT -disruptions unavoidable?
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Originally posted by Medicated Oil:
The day they accept any drop in minumum requirement, the rot start to set in.
The breakdown is due to insufficient or incompetent maintenance and not due to any overloading.
Fixing the maintenance solve the problem and not shift the blame to lousy excuse of population expansion.
It is a issue of whether they are willing to pay the money to fix the issue or keep on using tie wrap for temporary fix.
Where is the courage and commitment to fix the issue a few month ago ?
Is accepting the breakdown as a norm a solution ?
Who is getting complacent now ?
Each train carriage (M1/M2) at peak hour is definitely above 60 tonnes.
Distribute it to the number of axles per carriage.
I looked at the annual report of SMRT, it seems like their maintenance cost increased, so they didn't stinge on maintenance.
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Originally posted by βÎτά:
I can't find wheel load when I googled. I guess they don't use that as a yardstick for measuring load on tracks. Maybe you can put your wheel load theory on Wikipedia.
The axle load of a wheeled vehicle is the total weight felt by the roadway for all wheels connected to a given axle. Viewed another way, it is the fraction of total vehicle weight resting on a given axle. Axle load is an important design consideration in the engineering of roadways and railways, as both are designed to tolerate a maximum weight-per-axle (axle load); exceeding the maximum rated axle load will cause damage to the roadway or rail tracks.
http://en.wikipedia.org/wiki/Axle_load
this is not a cargo train when the load can exceed the safety factor or train in india wer pax stack up to the roof
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Originally posted by Medicated Oil:
The day they accept any drop in minumum requirement, the rot start to set in.
The breakdown is due to insufficient or incompetent maintenance and not due to any overloading.
Fixing the maintenance solve the problem and not shift the blame to lousy excuse of population expansion.
It is a issue of whether they are willing to pay the money to fix the issue or keep on using tie wrap for temporary fix.
Where is the courage and commitment to fix the issue a few month ago ?
Is accepting the breakdown as a norm a solution ?
Who is getting complacent now ?
Perhaps you can give us figures or reasons on why you think the carriages isn't overloaded.
Or is it a gut feeling?
OK.
Population increases also did not cause the escalation of HDB property prices, heavily burdened medical services and the bogged down public transportation system.
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Originally posted by lce:
this is not a cargo train when the load can exceed the safety factor
Cargo trains can carry heavier load.
Is there like a safety maximum total of passengers set by SMRT on the different carriages? Or it all depends on how much you can squeeze into the carriage.
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Why the expansion into bus services?
Cause they realised that the MRT system is already over capacity and they can't expand it anymore.
6-7 million population?
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Originally posted by βÎτά:
Cargo trains can carry heavier load.
Is there like a safety maximum total of passengers set by SMRT on the different carriages? Or it all depends on how much you can squeeze into the carriage.
then u hav to go bak to yr permissible axle loadsame as buildin , the stronger the foundation the higher it reach
as said track foundation sink, then alignment out , speedy wear n tear = poor maintenance
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Some of the axle loads for a particular trackbed.
Not sure about SMRT's trackbed, but I guess this is a good yardstick to know the axle load.
Singapore's MRT was contructed in the 80s, not sure if they upgraded the tracks thereafter.
http://www.gerb.com/de/bibliothek/downloads/dokumente/MFS_E.pdf
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Now is new singapore internet meme...
Boss ask staff why fail to meet target, staff replied "unavoidable"...
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Originally posted by βÎτά:
Some of the axle loads for a particular trackbed.
Not sure about SMRT's trackbed, but I guess this is a good yardstick to know the axle load.
Singapore's MRT was contructed in the 80s, not sure if they upgraded the tracks thereafter.
http://www.gerb.com/de/bibliothek/downloads/dokumente/MFS_E.pdf
standard track gauge started some 200 years ago n majority is still usin this gauge.as said its poor maintenance. due to soil movment overtime cozin out of tolerance
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2.2 Excitation Loads of Train-Track System onto Tunnel Structure
Using the above model, the excitation loads of the train-track system onto the tunnel structure can be obtained by computer simulation. The train concerned consists of 6 metro vehicles. The vehicle parameters under calculation are listed in Table 1.
The mass per unit length of the rail is 50 kg/m. The Hertzian contact coefficients are taken as kH = 81.9 GNm-2/3. With the sleeper spacing 55 cm, the parameters of the elastic support system are shown in Table 2.
Table 1 Calculation parameters of metro vehicle
Vehicle prameter
Value
Value
Car body mass Mc /t
37.0
Bogie spring stiffness kt /(kN·m-1)
2 080
Mass moment of inertia - car body Jt /(t·m2)
1 700
Bogie damping coefficient Ct /(kN·s·m-1)
240
Bogie mass Mt /t
3.60
Wheel spring stiffness kw /(kN·m-1)
2 450
Mass moment of inertia - bogie Jt /(t·m2)
9.62
Wheel damping coeff cw /(kN·s·m-1)
240
Vehicle full length Lc /m
19.52
Distance between bogie centers 2l /m
12.66
Fixed axle spacing 2a /m
2.30
Wheelset mass mw /t
1.70
Table 2 Track parameters
Parameter
Spring stiffness ki /(kN·m-1)
Damping coefficient ci /(kN·s·m-1)
Mass mi /kg
1st level (i=1)
0.8×105
102.0
3.0
2nd level (i=2)
0.8×105
120.0
15.0
3rd level (i=3)
0.8×105
120.0
3.0
Fig.4 illustrates a calculated force curve from the sleeper bottom and its spectrum, which can be employed as the dynamic loading onto the tunnel-ground system model. It clearly shows that the force is mainly induced by the loading weights of the cars.
(a) Time history (b) Spectrum
Fig.4 Excitation load of train-track system to the tunnel and its spectrum
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Rail claws on older MRT lines likely to be replaced
All 30,000 metal claws holding the power-supplying 'third rail' on the North-South and East-West MRT lines are likely to be replaced, in what appears to be a further step to prevent breakdowns in train services.
The Straits Times understands that rail operator SMRT has started sourcing for new-generation 'positive lock' claws. These can be bolted onto the rail sleepers - structures that support the track - and are far less likely to be undone by vibration over time.
Currently, the claws on the two ageing lines are not bolted but are merely held in place by the weight of the 'third rail', which supplies electricity to power the trains.
In the major breakdowns last December when more than 220,000 commuters were affected by service disruptions lasting five to seven hours, 21 of these claws along a stretch of the North-South Line were found to have been dislodged.
This caused a misalignment of the 'third rail' that, in turn, interrupted the power supply to the trains.
Since the breakdowns, SMRT has used plastic cable ties to fasten all the claws, which are spaced about 6m apart along each direction of the 90km network.
SMRT would not comment on the possibility of replacing the old claws with the new ones, which are already used in its newer lines such as the Circle Line and Changi Airport Extension of the East-West Line.
A company spokesman said the government-appointed inquiry that starts next week will be looking into the issues connected with the breakdown.
'It is best that all findings and recommendations be revealed through the Committee of Inquiry proceedings,' the spokesman said.
But sources said the claw replacement move is highly probable as the cable ties are only an interim measure.
The replacement exercise is estimated to cost between $5 million and $15 million, excluding labour.
As to who pays for this, urban transport expert Park Byung Joon said the answer is not straightforward in this case.
He noted that under an old financial arrangement, the Government pays for the rail infrastructure and SMRT owns, runs and maintains the system.
In 2010, a new financial regime was put in place. In it, the Government assumes ownership of operating assets, leasing them to the operator for a fee that will eventually fund asset replacement. SBS Transit's operating contract for the upcoming Downtown Line falls under this new arrangement.
'It is an interesting question, and I don't know if there is a right answer to that,' said Dr Park, who reckons replacement of the claws falls in a grey area between maintenance and an infrastructural upgrade.
'Should it be funded by taxpayers, or profits that the company had accumulated over the years?' asked Dr Park, who is programme head of the Master of Science programme in urban transport management at SIM University.
'Ultimately, there has to be consensus among all the interested parties.'
But Dr Lee Der-Horng, a transport researcher at the National University of Singapore, said the Government should pay, 'as this is an infrastructural work'.
However, what is of greater concern to him is whether the claws are the only problem.
He called for investigations to go deeper to find the root causes of the breakdowns, like vibration.
Preliminary findings by SMRT indicate that strong vibration along the city stretch of the North-South Line may have contributed to the claw dislodgement.
Tracks in the area are built on so-called 'floating slabs', designed to insulate nearby high-rise buildings from the vibration of passing trains.
CHRISTOPHER TAN
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After they finish replacing all the claws they can start packing in the passengers like dogs again.
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could it be the root cause is 10 years of neglect and non-maintenance?
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Originally posted by βÎτά:
2.2 Excitation Loads of Train-Track System onto Tunnel Structure
Using the above model, the excitation loads of the train-track system onto the tunnel structure can be obtained by computer simulation. The train concerned consists of 6 metro vehicles. The vehicle parameters under calculation are listed in Table 1.
The mass per unit length of the rail is 50 kg/m. The Hertzian contact coefficients are taken as kH = 81.9 GNm-2/3. With the sleeper spacing 55 cm, the parameters of the elastic support system are shown in Table 2.
Table 1 Calculation parameters of metro vehicle
Vehicle prameter
Value
Vehicle prameter
Value
Car body mass Mc /t
37.0
Bogie spring stiffness kt /(kN·m-1)
2 080
Mass moment of inertia - car body Jt /(t·m2)
1 700
Bogie damping coefficient Ct /(kN·s·m-1)
240
Bogie mass Mt /t
3.60
Wheel spring stiffness kw /(kN·m-1)
2 450
Mass moment of inertia - bogie Jt /(t·m2)
9.62
Wheel damping coeff cw /(kN·s·m-1)
240
Vehicle full length Lc /m
19.52
Distance between bogie centers 2l /m
12.66
Fixed axle spacing 2a /m
2.30
Wheelset mass mw /t
1.70
Table 2 Track parameters
Parameter
Spring stiffness ki /(kN·m-1)
Damping coefficient ci /(kN·s·m-1)
Mass mi /kg
1st level (i=1)
0.8×105
102.0
3.0
2nd level (i=2)
0.8×105
120.0
15.0
3rd level (i=3)
0.8×105
120.0
3.0
Fig.4 illustrates a calculated force curve from the sleeper bottom and its spectrum, which can be employed as the dynamic loading onto the tunnel-ground system model. It clearly shows that the force is mainly induced by the loading weights of the cars.
(a) Time history (b) Spectrum
Fig.4 Excitation load of train-track system to the tunnel and its spectrum
"It clearly shows that the force is mainly induced by the loading weights of the cars."
alamak, u r on solid ground. wat is loaded is not the major problem. the load distribution n safety factor must be considered wen they build the system. our mrt is not the first n not goin to be the last metro in the world.if i m correct, passenger safety factor is 1.5
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Originally posted by lce:
"It clearly shows that the force is mainly induced by the loading weights of the cars."
alamak, u r on solid ground. wat is loaded is not the major problem. the load distribution n safety factor must be considered wen they build the system. our mrt is not the first n not goin to be the last metro in the world.if i m correct, passenger safety factor is 1.5
omg!
I suppose loading won't affect vibrations, therefore it won't affect the tracks?
Then why India upgrade their freight tracks to carry above 20 tonnes axial load?
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Originally posted by βÎτά:
omg!
I suppose loading won't affect vibrations, therefore it won't affect the tracks?
Then why India upgrade their freight tracks to carry above 20 tonnes axial load?
wat link btw vibration n load on the track? is the track rotatin ?
the vibration is transfer from the wheel to the track
u oridi memtioned "freight tracks"
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Originally posted by lce:
wat link btw vibration n load on the track? is the track rotatin ?
the vibration is transfer from the wheel to the track
u oridi memtioned "freight tracks"
No comments.
Sighs......
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alamak, u r on solid ground. wat is loaded is not the major problem.
If a track connected to solid ground is inconsequential on the tracks, then perhaps we should have MRT running on wire tracks. Just remember to have very good load distribution.
I seriously hope pray you not working for the SMRT.
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Originally posted by βÎτά:
alamak, u r on solid ground. wat is loaded is not the major problem.
If a track connected to solid ground is inconsequential on the tracks, then perhaps we should have MRT running on wire tracks. Just remember to have very good load distribution.
I seriously hope pray you not working for the SMRT.
alamak didnt noe the tracks r directly lay on the ground , wonder wat the sleepers for?
noe wher u comin. the damage / wear is not on the track but on the bogie / wheel shafts / trunnions of the carriage wen heavily laden
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Now they extend closing of tracks to do major upgrading to tracks, after they complete, can afford to squeeze more passengers into carriages.
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Noticed even more crowded than before.
Times are bad.
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heard that it broke down again. this time at clementi
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Originally posted by charlize:
Noticed even more crowded than before.
Times are bad.
Those are dogs for sale in probably China or Vietnam, not the MRT trains.
They do look similar to the not so avid viewer.