diff --git a/DCC.cpp b/DCC.cpp
index ebf51de..29fa9d7 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -207,6 +207,9 @@ void DCC::writeCVBitMain(int cab, int cv, byte bNum, bool bValue)  {
 void DCC::setProgTrackSyncMain(bool on) {
   DCCWaveform::progTrackSyncMain=on;
 }
+void DCC::setProgTrackBoost(bool on) {
+  DCCWaveform::progTrackBoosted=on;
+}
 
 __FlashStringHelper* DCC::getMotorShieldName() {
   return shieldName;
diff --git a/DCC.h b/DCC.h
index 1e1058b..0e8fcc6 100644
--- a/DCC.h
+++ b/DCC.h
@@ -76,6 +76,7 @@ public:
   static void setAccessory(int aAdd, byte aNum, bool activate);
   static bool writeTextPacket(byte *b, int nBytes);
   static void setProgTrackSyncMain(bool on); // when true, prog track becomes driveable
+  static void setProgTrackBoost(bool on);    // when true, special prog track current limit does not apply
 
   // ACKable progtrack calls  bitresults callback 0,0 or -1, cv returns value or -1
   static void readCV(int cv, ACK_CALLBACK callback, bool blocking = false);
diff --git a/DCCEXParser.cpp b/DCCEXParser.cpp
index 82cd9d9..b52a968 100644
--- a/DCCEXParser.cpp
+++ b/DCCEXParser.cpp
@@ -45,6 +45,7 @@ const int HASH_KEYWORD_ACK = 3113;
 const int HASH_KEYWORD_ON = 2657;
 const int HASH_KEYWORD_DCC = 6436;
 const int HASH_KEYWORD_SLOW = -17209;
+const int HASH_KEYWORD_PROGBOOST = -6353;
 
 int DCCEXParser::stashP[MAX_PARAMS];
 bool DCCEXParser::stashBusy;
@@ -598,6 +599,11 @@ bool DCCEXParser::parseD(Print *stream, int params, int p[])
     case HASH_KEYWORD_DCC:
         DCCWaveform::setDiagnosticSlowWave(params >= 1 && p[1] == HASH_KEYWORD_SLOW);
         return true;
+
+    case HASH_KEYWORD_PROGBOOST:
+        DCC::setProgTrackBoost(true);
+	return true;
+
     default: // invalid/unknown
         break;
     }
diff --git a/DCCWaveform.cpp b/DCCWaveform.cpp
index dc4b503..a70ab16 100644
--- a/DCCWaveform.cpp
+++ b/DCCWaveform.cpp
@@ -30,6 +30,7 @@ DCCWaveform  DCCWaveform::progTrack(PREAMBLE_BITS_PROG, false);
 
 
 bool DCCWaveform::progTrackSyncMain=false; 
+bool DCCWaveform::progTrackBoosted=false; 
 VirtualTimer * DCCWaveform::interruptTimer=NULL;      
   
 void DCCWaveform::begin(MotorDriver * mainDriver, MotorDriver * progDriver, byte timerNumber) {
@@ -128,7 +129,7 @@ void DCCWaveform::checkPowerOverload() {
   if (millis() - lastSampleTaken  < sampleDelay) return;
   lastSampleTaken = millis();
   int tripValue= motorDriver->rawCurrentTripValue;
-  if (!isMainTrack && !ackPending && !progTrackSyncMain)
+  if (!isMainTrack && !ackPending && !progTrackSyncMain && !progTrackBoosted)
     tripValue=progTripValue;
   
   switch (powerMode) {
@@ -151,7 +152,10 @@ void DCCWaveform::checkPowerOverload() {
         DIAG(F("\n*** %S TRACK POWER OVERLOAD current=%d max=%d  offtime=%l ***\n"), isMainTrack ? F("MAIN") : F("PROG"), mA, maxmA, power_sample_overload_wait);
 	power_good_counter=0;
         sampleDelay = power_sample_overload_wait;
-	power_sample_overload_wait *= 2;
+	if (power_sample_overload_wait >= 10000)
+	    power_sample_overload_wait = 10000;
+	else
+	    power_sample_overload_wait *= 2;
       }
       break;
     case POWERMODE::OVERLOAD:
diff --git a/DCCWaveform.h b/DCCWaveform.h
index 5af7144..d607420 100644
--- a/DCCWaveform.h
+++ b/DCCWaveform.h
@@ -22,14 +22,16 @@
 #include "MotorDriver.h"
 #include "ArduinoTimers.h"
 
+// Wait times for power management. Unit: milliseconds
 const int  POWER_SAMPLE_ON_WAIT = 100;
 const int  POWER_SAMPLE_OFF_WAIT = 1000;
 const int  POWER_SAMPLE_OVERLOAD_WAIT = 20;
 
+// Ack time thresholds. Unit: microseconds
 const int  MIN_ACK_PULSE_DURATION = 2000;
 const int  MAX_ACK_PULSE_DURATION = 8500;
  
-
+// Number of preamble bits.
 const int   PREAMBLE_BITS_MAIN = 16;
 const int   PREAMBLE_BITS_PROG = 22;
 
@@ -67,6 +69,7 @@ class DCCWaveform {
     void setAckPending();  //prog track only
     byte getAck();               //prog track only 0=NACK, 1=ACK 2=keep waiting
     static bool progTrackSyncMain;  // true when prog track is a siding switched to main
+    static bool progTrackBoosted;   // true when prog track is not current limited
     inline void doAutoPowerOff() {
 	if (autoPowerOff) {
 	    setPowerMode(POWERMODE::OFF);