Question

Which of the following is/are correct labelling of \(P\), \(Q\), \(R\), \(S\), \(T\) with respect to the illustration of a suspension bridge as shown below?

• A. \(Q\) - Stay Cable, \(R\) - Pylon, \(T\) - Sag
• B. \(P\) - Anchorage, \(S\) - Pylon, \(T\) - Primary Suspended Cable
• C. \(Q\) - Stay Cable, \(R\) - Stiffening Deck, \(S\) - Pylon
• D. \(P\) - Stiffening Deck, \(R\) - Pylon, \(T\) - Primary Suspended Cable

Hint:

Match each letter to a standard suspension bridge part: tower = pylon, main dipping cable = primary suspended cable, sloped cable to ground = stay cable, ground block = anchorage, horizontal traffic girder = stiffening deck.

Answer 1

The Correct Option is B, C

This question checks if you know the standard vocabulary for a suspension bridge: pylon, primary suspended (main) cable, stay cable, anchorage and stiffening deck. Instead of naming each letter first, work option by option and test each claim against the picture.

1. (A) $Q$ - Stay Cable, $R$ - Pylon, $T$ - Sag: The stay cable part for $Q$ is fine, since $Q$ sits on the sloped cable running down to the ground anchor. But $R$ points at the horizontal deck member, not the vertical tower, so calling it a "pylon" is wrong. And "sag" is only a number (the drop of the cable at mid span), it is not a physical member you can point an arrow at, so $T$ cannot be "sag" either. This option fails.
2. (B) $P$ - Anchorage, $S$ - Pylon, $T$ - Primary Suspended Cable: $P$ marks the spot where the cable disappears into the ground block, which is exactly the anchorage. $S$ sits right beside the vertical tower at deck level, so it is the pylon. $T$ sits on the sagging cable between the towers, which is the primary suspended (main) cable. All three checks pass, so this option is correct.
3. (C) $Q$ - Stay Cable, $R$ - Stiffening Deck, $S$ - Pylon: $Q$ is the stay cable as shown above. $R$ is the horizontal girder that the hangers connect to and that supports the roadway, the stiffening deck. $S$ is the pylon, as also shown in (B). All three checks pass, so this option is correct too.
4. (D) $P$ - Stiffening Deck, $R$ - Pylon, $T$ - Primary Suspended Cable: $T$ being the primary suspended cable is right, but $P$ is at the ground anchor block, not the deck, and $R$ is the deck member, not the tower. Two of the three labels are swapped, so this option fails.

Only options (B) and (C) survive the check against the figure.

Let's summarize:

• Pylon = vertical tower; stay cable = sloped cable segment to the ground anchor; primary suspended cable = the main dipping cable between towers; stiffening deck = the horizontal traffic girder; anchorage = the ground block holding the cable end.
• "Sag" is a dimension, never a labelled component, so any option naming a letter "sag" is automatically wrong.

The correct labelling is given by options (B) and (C).