Niagara Regional Road 3A

Infobox road
marker_

state=
highway_name=Niagara Regional Road 3A
name_notes=
type=
route=
alternate_name=Welland Street
Mellanby Avenue
maint=the Niagara Region transportation department
section=
length_km=1.2
length_round=
length_ref= [http://maps.google.ca/maps?f=d&hl=en&geocode=&saddr=Welland+St+%26+Main+St+E,+Port+Colborne,+ON&daddr=42.896356,-79.245994+to:Main+St+W+and+Mellanby+Ave&mrcr=0,1&mrsp=1&sz=16&mra=dpe&sll=42.900128,-79.246466&sspn=0.00951,0.019677&ie=UTF8&z=16&om=1]
length_notes=
established=
decommissioned=
direction=East/West
direction_a=East
terminus_a=Main Street East (Regional Road 3)
beltway_city=
junction=
direction_b=West
terminus_b=Main Street West (Regional Road 3)
counties=Niagara Region
rural_municipalities=
cities=Port Colborne
system=
previous_type=
previous_route=
next_type=
next_route=
browse=
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Niagara Regional Road 3A—parts of which are also named Welland Street and Mellanby Avenue—is a short regional road in Port Colborne, Ontario, Canada. It bypasses the Main Street (Regional Road 3) bridge over the Welland Canal. When the Main Street bridge is raised, the Regional Road 3A crossing closes to allow traffic to pass uninterrupted between the East and West sides of Port Colborne.

Prior to reorganization of the regional road network in 2002, the Welland Street portion was called Regional Road 68 and the Mellanby Road portion was Regional Road 503, although it was—and still is—signed as a portion of Highway 3, even though the highway was downloaded through Port Colborne in 1998. Regional Road 3A is the first and only suffixed route in the Niagara regional road network.