diff --git a/src/measurements/MeasurementContainer.js b/src/measurements/MeasurementContainer.js
index 97b7f7d..4a6d107 100644
--- a/src/measurements/MeasurementContainer.js
+++ b/src/measurements/MeasurementContainer.js
@@ -92,7 +92,16 @@ class MeasurementContainer {
     if (!this._currentVariant) {
       throw new Error('Variant must be specified before position');
     }
+
+    // Turn string positions into numeric values
+    if (typeof positionValue == "string") {
+      positionValue = positionValue == "upstream" ? Number.NEGATIVE_INFINITY : positionValue;
+      positionValue = positionValue == "atEquipment" ? 0.0 : positionValue;
+      positionValue = positionValue == "downstream" ? Number.POSITIVE_INFINITY : positionValue;
+    }
+
     this._currentPosition = positionValue;
+    
     return this;
   }