"Chris Brown"
I don't agree with the idea that WMATA should just keep ordering 7k's to replace the 2k and 3k cars. I believe it is much smarter to make some design changes with the 8k cars. The reason for this comes down to having variety in the fleet.. which helps to avoid a situation where the entire fleet is compromised by some future defect identified.
Per example.. the 1k and 4K cars. After decades the 1k cars were discovered to not be crash worthy.
The designers of the 1k cars knew going in that they would not be as crash worth as common carrier passenger cars. They sacrificed crash worthiness for light weight, to compensate for the crash worthiness a robust double redundant train control and signal system was employed. Problem was WMATA did not maintain that train control and signal system to its designed specification which would have prevented the event of 06 22 2009.
Then later the 4k cars were taken out of service because of a defect. Then again moved to the center of trains because of another problem.
That defect would have been removed had WMATA done the mid life rehabilitation to the 4k cars upon completion of of the mid life rehabilitation 3k cars.
This is why the entire fleet cannot be the same. You need variety for situations like this where defects are found down the road.
Car design variety creates spare parts inventory issues. The 4k cars were the orphans of the fleet because of their numbers and the lack of commonality of parts.
Virtually all of defect discovered in the 7k cars were correct through software.
As far as I am concerned WMATA should sign another contract with Kawasaki to build more 7k cars and or build a new open gangway car shell fitted with the same hardware in the 7k cars.
I don't agree with the idea that WMATA should just keep ordering 7k's to replace the 2k and 3k cars. I believe it is much smarter to make some design changes with the 8k cars. The reason for this comes down to having variety in the fleet.. which helps to avoid a situation where the entire fleet is compromised by some future defect identified.
Per example.. the 1k and 4K cars. After decades the 1k cars were discovered to not be crash worthy.
The designers of the 1k cars knew going in that they would not be as crash worth as common carrier passenger cars. They sacrificed crash worthiness for light weight, to compensate for the crash worthiness a robust double redundant train control and signal system was employed. Problem was WMATA did not maintain that train control and signal system to its designed specification which would have prevented the event of 06 22 2009.
Then later the 4k cars were taken out of service because of a defect. Then again moved to the center of trains because of another problem.
That defect would have been removed had WMATA done the mid life rehabilitation to the 4k cars upon completion of of the mid life rehabilitation 3k cars.
This is why the entire fleet cannot be the same. You need variety for situations like this where defects are found down the road.
Car design variety creates spare parts inventory issues. The 4k cars were the orphans of the fleet because of their numbers and the lack of commonality of parts.
Virtually all of defect discovered in the 7k cars were correct through software.
As far as I am concerned WMATA should sign another contract with Kawasaki to build more 7k cars and or build a new open gangway car shell fitted with the same hardware in the 7k cars.
John in the sand box of Maryland's eastern shore.
