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From page 17... ... SECTION 6 17 STD/PS Considerations 6.1 Consequences of Having an STD/PS Below are the consequences of a secondary system in a CBTC project: 6.1.1 Investment Effort A secondary system requires a significant investment effort to deploy. In comparison to deploying CBTC without STD/PS, a CBTC project with STD/PS requires a higher capital cost and a longer schedule due to: • More effort to design the STD/PS and the added complexity of integrating the STD/PS with CBTC. • More equipment to purchase and install. Installation is usually the major cost and could be a major impact on the schedule for signaling upgrade projects. Read the entire page →
From page 18... ... SECTION 6 – STD/PS CONSIDERATIONS 18 instantaneous speed of the trains, continuously calculates the varying safe separation which results in minimum possible distance between two trains at all times. The conventional signaling system may be capable of enforcing signals at stop, via devices mounted on the roadbed. The train stop arm activating a tripcock which opens the emergency brake lines on the train is one such example. To have the CBTC system provide its optimal train separation, allowing trains to be closer to each other than the conventional system, the conventional train separation enforcement system must not affect CBTC trains. The transit agency may also want to avoid the issue of having CBTC trains passing non‐proceed signals, even if those signals are dedicated for the non‐CBTC trains. In rare cases, transit agencies have decided that CBTC trains should respect the conventional signaling system with non‐optimal train separation. There are several methods to avoid the conventional signaling system impeding on CBTC performance: • Disable the enforcement system and have a separation signal which is clearly only for the non‐CBTC trains, such as a particular color. • Have the CBTC system override the enforcement system and override the signals so that signals present an aspect different for the CBTC trains than for the non‐CBTC trains. For example, a solid green indicates STD/PS proceed and a flashing green indicates CBTC proceed. This approach increases not only the complexity of the CBTC itself but also the complexity of the secondary system. Read the entire page →
From page 19... ... SECTION 6 – STD/PS CONSIDERATIONS 19 Table 4: Examples of STD/PS Drawbacks (percentages are illustrative and will vary depending on system characteristics) Type Category Sub‐category Investment effort (%) Read the entire page →
From page 20... ... SECTION 6 – STD/PS CONSIDERATIONS 20 Table 5: Level of Consequences of STD/PS – Average effort of deployment and impact on maintenance and operation (percentages are illustrative and will vary depending on system characteristics) This graph shows the comparative level of effort required for each type of secondary system. 1. Read the entire page →
From page 21... ... SECTION 6 – STD/PS CONSIDERATIONS 21 6.2 Consequences of Having No or Minimal STD/PS Not having an STD/PS could have the following impacts during initial deployment phases and during revenue service. 6.2.1 Relying Heavily on Operating Procedures Handling of non‐CBTC equipped trains, and trains with CBTC failure have been very challenging for systems without STD/PS in terms of the impact on system availability and operations. For equipment failures, as an example, location tracking of trains with CBTC failure is not possible, which makes automatic protection unlikely. In such cases, one must manually ensure: • Protection of the non‐equipped train or train with CBTC failure from the other CBTC trains. • Protection of CBTC trains from the non‐equipped train or train with CBTC failure. Read the entire page →

From page 17...

... SECTION 6 17 STD/PS Considerations 6.1 Consequences of Having an STD/PS Below are the consequences of a secondary system in a CBTC project: 6.1.1 Investment Effort A secondary system requires a significant investment effort to deploy. In comparison to deploying CBTC without STD/PS, a CBTC project with STD/PS requires a higher capital cost and a longer schedule due to: • More effort to design the STD/PS and the added complexity of integrating the STD/PS with CBTC. • More equipment to purchase and install. Installation is usually the major cost and could be a major impact on the schedule for signaling upgrade projects.

Read the entire page →

From page 18...

... SECTION 6 – STD/PS CONSIDERATIONS 18 instantaneous speed of the trains, continuously calculates the varying safe separation which results in minimum possible distance between two trains at all times. The conventional signaling system may be capable of enforcing signals at stop, via devices mounted on the roadbed. The train stop arm activating a tripcock which opens the emergency brake lines on the train is one such example. To have the CBTC system provide its optimal train separation, allowing trains to be closer to each other than the conventional system, the conventional train separation enforcement system must not affect CBTC trains. The transit agency may also want to avoid the issue of having CBTC trains passing non‐proceed signals, even if those signals are dedicated for the non‐CBTC trains. In rare cases, transit agencies have decided that CBTC trains should respect the conventional signaling system with non‐optimal train separation. There are several methods to avoid the conventional signaling system impeding on CBTC performance: • Disable the enforcement system and have a separation signal which is clearly only for the non‐CBTC trains, such as a particular color. • Have the CBTC system override the enforcement system and override the signals so that signals present an aspect different for the CBTC trains than for the non‐CBTC trains. For example, a solid green indicates STD/PS proceed and a flashing green indicates CBTC proceed. This approach increases not only the complexity of the CBTC itself but also the complexity of the secondary system.

Read the entire page →

From page 19...

... SECTION 6 – STD/PS CONSIDERATIONS 19 Table 4: Examples of STD/PS Drawbacks (percentages are illustrative and will vary depending on system characteristics) Type Category Sub‐category Investment effort (%)

Read the entire page →

From page 20...

... SECTION 6 – STD/PS CONSIDERATIONS 20 Table 5: Level of Consequences of STD/PS – Average effort of deployment and impact on maintenance and operation (percentages are illustrative and will vary depending on system characteristics) This graph shows the comparative level of effort required for each type of secondary system. 1.

Read the entire page →

From page 21...

... SECTION 6 – STD/PS CONSIDERATIONS 21 6.2 Consequences of Having No or Minimal STD/PS Not having an STD/PS could have the following impacts during initial deployment phases and during revenue service. 6.2.1 Relying Heavily on Operating Procedures Handling of non‐CBTC equipped trains, and trains with CBTC failure have been very challenging for systems without STD/PS in terms of the impact on system availability and operations. For equipment failures, as an example, location tracking of trains with CBTC failure is not possible, which makes automatic protection unlikely. In such cases, one must manually ensure: • Protection of the non‐equipped train or train with CBTC failure from the other CBTC trains. • Protection of CBTC trains from the non‐equipped train or train with CBTC failure.

Read the entire page →

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