\documentclass{standalone}
\pagestyle{empty}
\usepackage{tikz}

\begin{document}

\begin{tikzpicture}
\clip (-2,-.1) rectangle (2,2);
\draw[thick]  (-2,0)--(2,0);
\foreach \j in {0,.5,...,2} \draw [very thin, cyan] (\j,0)--(\j+2, 2);

\foreach \j in {0,-.5,...,-2} \draw [very thin,cyan] (\j,0)--(\j-2, 2);

\foreach \j in {-2,-1.5,...,2} \draw [very thin,lime] (0,0)--(\j, 2);

\node at (1.25,.5) {$u=u_+$};
\node at (-1.25,.5) {$u=u_-$};
\node at (0,1.5) {$u=\frac{x}{t}$};

\end{tikzpicture}
\end{document}
