Given:

$g_1=-4\mathrm{.}00\%$ intersects $g_2=+3\mathrm{.}80\%$ at PVI of $52+00$ with

elev ${?}_{\text{P}\text{V}\text{I}}=1261\mathrm{.}50\text{'}$ with $L=?$ feet. Design an equal

tangent parabolic curve to meet a railroad crossing,

which exists at sta $53+50$ with an elev of $1271\mathrm{.}20\text{'}.$