(I)A dangerous condition of a public highway, road, or street which physically interferes with the movement of traffic on the paved portion, if paved, or on the portion customarily used for travel by motor vehicles, if unpaved, of any public highway, road, street, or sidewalk within the corporate limits of any municipality, or of any highway which is a part of the federal interstate highway system or the federal primary highway system, or of any highway which is a part of the federal secondary highway system, or of any highway which is a part of the state highway system on that portion of such highway, road, street, or sidewalk which was designed and intended for public travel or parking thereon. As used in this section, the phrase “physically interferes with the movement of traffic” shall not include traffic signs, signals, or markings, or the lack thereof. Nothing in this subparagraph (I) shall preclude a particular dangerous accumulation of snow, ice, sand, or gravel from being found to constitute a dangerous condition in the surface of a public roadway when the entity fails to use existing means available to it for removal or mitigation of such accumulation and when the public entity had actual notice through the proper public official responsible for the roadway and had a reasonable time to act.