Tutor Perini/Frontier-Kemper JV to construct tunnels for Purple Line Extension Section 3 in LA July 5, 2018 | North America News The Tutor Perini/Frontier- Kemper Joint Venture has secured a USD410-million contract from the Los Angeles County Metropolitan Transportation Authority (LA Metro) for the Purple Line Extension Section... This content is available to only subscribers. Username or E-mail Password Remember Me Forgot Password