An Air Carrier pilot reported aircraft taxiing on Taxiway ED in front of the Rwy 17R landing threshold at DEN can be a distraction to aircraft on short final as they appear to be crossing the runway. The reporter recommends notes on charts to warn crews.

Narrative

This report concerns confusion regarding the fact that ATC in DEN (Ground and Tower) can allow certain aircraft to go on to taxiway ED below aircraft landing on Runway 17R; if their tail height is low enough (20.55 feet or less). This includes some RJ's; smaller aircraft; and vehicle traffic. This fact is not shown in any of the information given to pilots on the Jepp 10-7 or 10-9 pages for DEN; nor in any company communications I am aware of. We were cleared to land for a Visual Approach to 17R in DEN and at approximately 200 feet; I noticed a CRJ-200 was turning the corner at the intersection of taxiway M and ED. Normally aircraft stop soon after as there is an immediate hold short line on taxiway ED for aircraft landing on Runway 17R. But this aircraft continued on and after a few double takes; I realized the aircraft was in the Runway Protection Zone (RPZ) and continuing down taxiway ED. I pointed this out to the First Officer who was flying but as the RJ was going under the nose and quickly spilling out to the left; we determined a go around wouldn't have created any additional spacing from the RJ and in any case; felt assured there was no collision potential based on our height and the geometry of the approach to the runway whose threshold was considerably past taxiway ED. Still; it was unexpected to say the least and the fact Tower said nothing added to the confusion as to whether this was an incursion; though it seemed hard to imagine that both Ground and Tower would have missed such an obvious infraction in day VMC conditions if that were the case. The landing and taxi to the gate were uneventful and due to radio congestion on both Tower and Ground; we decided the best course was to wait until we were at the gate to talk to them about it. Surprisingly; a phone number to the Tower is not the easiest thing to find and I called our Rep in Operations for help and he got me a number to DEN TRACON; who then got me a number to the Tower. I then talked with [Tower Supervisor] who was very helpful and he explained that; though it happens rarely; aircraft that are less than 20.55 feet in height can taxi on ED while aircraft are landing on Runway 17R. I explained that this isn't stated anywhere that I am aware of and from a pilot's perspective; could create an unnecessary go-around. There are several issues here. First; unless I'm just ignorant of this knowledge being disseminated somewhere; most pilots are not aware of this exception and probably haven't seen it's occurrence from the ground or air. Second is that even knowing this exception; pilots would have to know which aircraft the exception applies to specifically (which is basically the CRJ 100/200 series or smaller aircraft; and vehicles). The CRJ 700/900 is too tall. The like-sized Embraer ERJ-145 and later series are too tall. All the larger E-series Embraer's are too tall. The Dornier Jets are too tall. Basically; pilots need to know of the limited exception for CRJ 100/200 and smaller aircraft (Pilatus; Metroliner's; BE-1900's; etc.) that are under 20.55 feet in height; and vehicles. Third is the fact that if this rare exception suddenly manifests itself; as it did for us on very short final; Tower must give the pilots a heads-up. Though the taxiing aircraft would be talking with Ground; one assumes Ground and Tower are still in close coordination; especially at a major airport like DEN. In any case; we both agreed that this would best be brought up to Flight Operations to make them aware of this unique scenario and hopefully to get the word out to pilots; and perhaps the DEN 10-7 page could make a comment about it as well. With all the ingrained personal experience pilots have of the Hotspot hold short line at taxiway M and ED and the obvious emphasis on avoiding incursions; not to mention all the times Ground tells you to hurry down ED once you're cleared to avoid issues with aircraft landing on Runway 17R; having an aircraft taxi under you as you yourself are landing on Runway 17R is; as I said; unexpected to say the least.