The reason that they use lights on the top of those overpasses is because the traffic lights, overall, are more efficient at handling the expected volumes of traffic than a traditional cloverleaf.
Most of these intersections will see lopsided rushhour traffic; one way for morning, the opposite way for evening. They can manipulate the turning lane lights depending on traffic patterns, keeping the majority of the cars moving. The alternative is a cloverleaf whose onramp is backed up for 2 kms during rush hour... On top of that, cloverleafs occupy a lot of real estate.
|