Question 1185202
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The half axis in the x direction is 6.10/2 = 3.05m; the half axis in the y direction is 8m.  The equation (assuming for simplicity the center of the ellipse at the level of the road and in the middle of the tunnel) is<br>
{{{x^2/3.05^2+y^2/8^2=1}}}<br>
Solving for y,<br>
{{{y=8*sqrt(1-x^2/3.05^2)}}}<br>
Plug in x=2.55 to allow the 0.5m clearance from the wall of the tunnel and evaluate.<br>
My answer: 4.389m<br>