a new parallel taxiway (oh for such a thing for 23L/5R)
This would represent little more than a white-elephant cosmetic investment at MAN. Having been delivered at very considerable expense (circa 300M due to challenging topography and two tunnels), a 23L/05R parallel taxiway would add very few runway slots over and above present capability. Given the concentration of existing runway access points at the 23L threshold end, dedicated use of 23L for departures and 05R for arrivals when in dual mode allows for that runway to be very fully utilised already. A parallel taxiway offers enhanced flexibility in choice of runway-in-use configuration, but it doesn't directly increase the movement capability of the runway. Remodelling of the exits could conceivably add a couple of runway slots per hour, but that wouldn't come close to justifying the cost of provision. Meanwhile, if MAG did fortuitously find an extra GBP300M to spend, initiatives such as providing additional apron space and stands for T3 in conjunction with enhanced passenger handling capacity there would be a much more compelling investment.