What on-line Apps would give me the elevation of any location I want?

For example, I would like to plan an exit route for my family in case a flood should come in this area.  Some of the ROADS go thigh ground, but there're some dips along the way.  I need a way to find what places along a highway might dip below the flood plain. I t grid sing Google maps, but could not find a quick way to find elevation information.
Any ideas?
Maybe a Android App for my smartphone or iPhone?


Many Weather sites have elevation maps.Perhaps you'd be better off contacting your local environmental authority - I'm sure you have something like that? Or at least the national environment AGENCY, whoever that may be. They would probably provide you with the most accurate information and advice.One source is the geographic topology maps issued by the government, but these often are very COURSE ant only show levels in 40foot marks. So you might be in a 35 foot hole and not it on the map.
https://education.usgs.gov/lessons/geospatialwebsites.html
I did a Google search and found there is an App that will give you a map like Google and let yu pick elevation for any point. But there are no topographical contours.
You use topographical** map to see  if yu can do a witless link from your house to grandma without going up on the ROOF.

**
QUOTE

top·o·graph·i·cal
relating to the arrangement or accurate representation of the physical features of an area.
"the topographical features of the river valley"
    (of a work of art or an artist) dealing with or depicting places (especially towns), buildings, and natural prospects in a realistic and detailed manner.

I thought you were escaping an impending flood....not setting up wireless to Grandma's house...