Air carrier Captain reported a frequent runway icing hazard on LGA's runway 04-22 that is not depicted in charts or NOTAMs. The Captain states that due to the unique construction of the elevated runway over water; a section of the runway freezes earlier than the rest creating a reduced braking action hazard.

Narrative

The portion of LGA's Runway 4/22 that is north of the crossing Runway 13/31 is supported by a pier over water. This portion of Runway 4/22 is exactly like a roadway bridge whereby it freezes before the portion of the road on grade. This elevated runway portion freezes before the rest of the runway; which is on grade and not exposed to wind and water from underneath in cold temperatures. This is particularly hazardous for large/heavy type jet aircraft landing on Runway 4. If the aircraft is not slowed to a safe runway turnoff speed by the time it crosses Runway 13/31; the braking action may be severely reduced due to the phenomenon described above. The north portion of Runway 22 prior to Runway 13/31 is also hazardous to any sized aircraft landing Runway 22 as this is the touchdown zone; a time critical for aircraft directional control. I can find no written warning of this hazard in any company or FAA or other government source to warn pilots of this hazard. Experienced pilots operating at LGA know of this; and Captains and check air-pilots warn newer pilots about this phenomenon; and word of mouth seems to be the only way this critical safety information is disseminated. Please name a note of this phenomenon on the 10-9 pages for LGA; and any other runway in the U.S. airspace system that has a structure-elevated runway.