High speed taxiway
 

In my Air Law and ATC Procedures book it states the following (translated):

A High Speed Taxiway should allow an aircraft to vacate a wet runway at:

- 93 km/h for Aerodrome codes 3 and 4,
- 65 km/h for Aerodrome codes 1 and 2.

If that's of any use.

On some Buses FCOM 3.1.20 reports Taxi speed limitation.
In my case with more than 76 tons "do not exceed a taxi speed of 20 Kts during a turn".

56 kts ICAO

Be careful applying a blanket figure during operations. There are many variables which you should consider, such as;

Runway width
Taxiway width
Runway/ taxiway corner fillets, or not
Contamination present on runway/ taxiway
Length of taxiway and potential taxiway over-run area
Aircraft serviceability
Wind, especially crosswind
Rate of decelleration
Autobrake stopping distance
Experience level of both crew
Traffic situation on taxiway and on approach behind you

There are more, but you get the gist? Account for all the variables and have a PLAN, based on these variables, but remain flexible enough to modify that plan if something changes/ isn't working. Be careful turning off at high speed....

PP

According to my company's SOPs:
For Boeing 777 (Cat. D):
Normal taxi speed = 20 kts
Taxi during turn = max. 10 kts
Maximum taxi speed on straight taxiways = 30 kts.

We had exactly this question in my last sim-check, and the instructor told us that, in a high-speed taxiway, the maximum taxi speed of the aircraft applies.
So in case of a 777, that would be 30 knots.
Likewise for any other aircraft type (according to my airline), it would be whatever is written in the FCOM chapter "Limitations".

I doubt whether any aircraft should vacate the runway at 93 km/h, because it would mean that part of your landing is still on a taxiway. Another sentence in the OM-A says that the aircraft should reach taxi-speed before turning off the runway.

So I think the answer to the question is: the aircraft's maximum taxi speed.

60 kts check the jepps air traffic control definitions section or in the jepps legend cant remember exactly :ok:

Jeppesen Introduction, Chart Glossary:

HIGH SPEED TAXIWAY / TURNOFF (HST) — A long
radius taxiway designed and provided with lighting or
marking to define the path of an aircraft, traveling at
high speed (up to 60 knots), from the runway center
to a point on the center of a taxiway. Also referred to
as long radius exit or turnoff taxiway. The high speed
taxiway is designed to expedite aircraft turning off
the runway after landing, thus reducing runway occupancy
time.


But then again, for runway code numbers 3 and 4 (lenght>1200m), the high speed taxiway are supposed to be designed for turn off with speed of 50kts (93km/h) in wet conditions. (found in a JAA Air Law book)

The ICAO rapid exit taxiway design speed is 50 knots (93 kph) for Code 3 and 4 aircraft for exit speeds under wet conditions.

In setting this speed, there is something of a safety margin built in, and the assumption is that the aircraft is usually travelling slower when it exits – the nominal turnoff speed is 30 knots for Code 3 and 4 (Aerodrome design manual Part 2 – section 1.3.12).

It makes sense that the operating manuals are targeting something like the 30 knot mark, because that leaves all the safety margins in place for the unusual operation.

The design of the rapid exit taxiway is rather more than just a curve radius for maximum speed. It also provides for a straight distance after the turn-off curve sufficient for an exiting aircraft to come to a full stop clear of any intersecting taxiways. It is based on modest lateral accelerations, and very gentle deceleration rates for the curved section and slightly more (but still gentle) for the straight sections.

I can't recall any accidents as a direct consequence of an aircraft using a rapid exit taxiway (although that statement is so bold as to beg correction. Update: searched the NTSB accident database from 1990 to 2008 and found none), so ICAO has probably got the numbers reasonably right.

From memory, I concur with the Jep 60kn. BUT, of course, pre-applying common sense.