Small Aircraft; High Wing; 1 Eng; Fixed Gear
Flight Crew Private
Flight Crew Last 90 Days 5; Flight Crew Total 116.4; Flight Crew Type 16
Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Landed As Precaution; Flight Crew Diverted
Human Factors; Aircraft
During a flight with a pilot friend a vibration occurred in the engine.  We determined we would not make it back safely to an airport and needed alternative plans.  A road was off our wing and with power pulled to idle we determined that was the only course of action we had.  We paralleled the highway; contacted emergency service on 121.5 and indicated an emergency and that we were landing on a highway.  Once clear of traffic I landed the Stinson in the southbound lane.  I contacted 121.5 once again that there were no injuries or others involved.  The FAA was notified and was on scene hours later.  They released the plane to me calling it an occurrence with no damage to property or persons. They informed me I followed regulations and acted in accordance with emergency procedures.
Stinson pilot experiences engine vibration and elects to land on a highway as a precaution with no injuries or damage to the aircraft.