View Full Version : Runway Stripes - I've always wondered...
3rd Aug 2012, 02:22
I was reminded last evening that I have never figured out why, if you follow the yellow line out of the taxiway onto the runway, the yellow line terminates offset to the runway centerline markings. Why?
A reminder that you're not totally commintted to the takeoff, you can still veer off, and slink back to the apron?
Big Pistons Forever
3rd Aug 2012, 02:59
Are yellow lines on UK runways on the left side ?
3rd Aug 2012, 04:29
I was reminded last evening that I have never figured out why, if you follow the yellow line out of the taxiway onto the runway,
You should not, the yellow lines are high speed exit lines for the opposite runway ,not line up ones.
Wonder what color comes out of a mix of yellow and white :E
India Four Two
3rd Aug 2012, 06:07
I don't think Pilot DAR is talking about high speed exits, but conventional taxiway centre line lead-in to the runway.
I have noticed that too but never bothered to think why until now. :sad:
The FAA bible on this subject is http://www.faa.gov/documentLibrary/media/Advisory_Circular/150_5340_1k_consolidated.pdf
Page 32 is the relevant text:
For taxiways that intersect a runway at any other locations than at the runway end, as shown in figure 14, the taxiway centerline marking curves onto the runway and extends parallel to the runway centerline marking for a distance of 200 feet (61 m) beyond the point of tangency with the runway centerline or terminates at the point of contact with the displaced threshold bar, whichever is less. As shown in figures 14 and 15, these lead-on and lead-off taxiway centerlines are 3 feet (1.0 m) from the runway centerline when measured near-edge to near-edge.
Figure 14 is on page 75.
The text doesn't explain why the 3' gap is required but I suppose it might be to avoid partially obscuring the yellow line by the runway centre line markings.
BTW, I'm pleased to see that someone at the FAA has some sense and converted 3' to 1.0 m, instead of 0.91 m!
3rd Aug 2012, 07:29
The yellow lines are exit lines, not entry lines (both normal exits and high speed exits have those lines). Thou shalt not follow the yellow lines when lining up.
3rd Aug 2012, 07:59
Just to put another spanner in the works, some runway markings in some countries are yellow. :}
3rd Aug 2012, 08:36
DAR its so you don't bang down the lighting. Although when its 150m you depart with a combination of brail, ILS locator and side lights out the corner of your eye.
In some runways the center line lighting is offset from the center slightly to one side then the lead in line takes you to the true center.
3rd Aug 2012, 08:46
The yellow lines are exit lines, not entry linesIn Germany, perhaps, but not in the UK apparentlyCAP 168, para 4.6.1
Where the taxiway leads onto or off the runway, the yellow line should be curved into the nearside of and 0.75 m ± 0.15 m from the runway centreline, except at the runway threshold where the yellow line should be discontinued at the edge of the runway...
3rd Aug 2012, 08:55
Most of europe is the same as the UK. You have to watch sometimes that the bloke that designed the turn at the end wasn't a bit to optomistic with the turning circle. If you follow some of them you will take the end lights out.
Norway has yellow runway markings and extremely small runway numbers but it works quite well with snow next to the runway.
3rd Aug 2012, 12:06
There's a UK CAA book that will tell you just about everything you want to know about airport markings and signs - CAP637 (http://www.caa.co.uk/docs/33/CAP637.PDF). Chapter 2, Page 3 tells you the facts. The doc is broadly consistent with ICAO Annex 14 etc. but I think it includes details of one or two systems used in the UK but for which there are no international standards.
The reason that the white (runway) markings and the yellow (taxiway) markings are separate is so that they can both be clearly seen and one does cover up the other.
As an aside, you might also notice that many of the centreline markings are not aligned with the centreline lights but are offset by a few inches. I've heard a few odd conspiracy theories for why this is done. But the simple truth is that it means that the lines can be repainted without spraying paint all over the light fittings.
The offset present, for whatever reason, means that exits are a heck of a lot easier to pick out at night when barreling along the runway in a big aircraft...