diff --git a/traffxml/traff_model.cpp b/traffxml/traff_model.cpp
index 7479f713f..ec981e489 100644
--- a/traffxml/traff_model.cpp
+++ b/traffxml/traff_model.cpp
@@ -138,6 +138,12 @@ IsoTime::IsoTime(std::tm tm)
   : m_tm(tm)
 {}
 
+bool IsoTime::IsPast()
+{
+  std::time_t t_now = std::time(nullptr);
+  std::time_t t_tm = timegm(&m_tm);
+  return t_tm < t_now;
+}
 
 bool operator< (IsoTime lhs, IsoTime rhs)
 {
diff --git a/traffxml/traff_model.hpp b/traffxml/traff_model.hpp
index 221b0c500..0ab998e94 100644
--- a/traffxml/traff_model.hpp
+++ b/traffxml/traff_model.hpp
@@ -65,6 +65,15 @@ public:
    */
   static IsoTime Now();
 
+  /**
+   * @brief Whether the instance refers to a point of time in the past.
+   *
+   * Comparison is against system time.
+   *
+   * @return true if in the past, false of not.
+   */
+  bool IsPast();
+
   friend bool operator< (IsoTime lhs, IsoTime rhs);
   friend bool operator> (IsoTime lhs, IsoTime rhs);
 private: