Index: train_cmd.cpp
===================================================================
--- train_cmd.cpp	(revision 17064)
+++ train_cmd.cpp	(working copy)
@@ -2306,7 +2306,14 @@
 {
 	bool sound = false;
 
-	if ((v->vehstatus & VS_TRAIN_SLOWING) || v->load_unload_time_rem != 0 || v->cur_speed < 2) {
+	/* Do not show any smoke/locomotive effect when train is slowin down or
+	 * player clicks stop button in train's window or
+	 * train is loading/unloading or
+	 * train's current speed is less than 2 km/h or
+	 * or train is entering station with an order to stop there and is gradually slowing down to stop there with speed equal as station-tile maximum entering speed. */
+	if ((v->vehstatus & VS_TRAIN_SLOWING) || (v->vehstatus & VS_STOPPED) || v->load_unload_time_rem != 0 || v->cur_speed < 2 ||
+		 (IsTileType(v->tile, MP_STATION) && v->IsFrontEngine() && v->current_order.ShouldStopAtStation(v, GetStationIndex(v->tile)) &&
+		  v->cur_speed >= ((Station::GetByTile(v->tile)->GetPlatformLength(v->tile, DirToDiagDir(v->direction)) >> (2 >> v->current_order.GetStopLocation())) * 25))) {
 		return;
 	}
 
@@ -2348,24 +2355,43 @@
 
 		switch (effect_type) {
 			case 0:
-				/* steam smoke. */
-				if (GB(v->tick_counter, 0, 4) == 0) {
+				/* Steam smoke - amount is gradually falling until train reaches its maximum speed, after that it's normal.
+			 	 * Details: while train's current speed is gradually
+			 	 * increasing, steam plumes' density decreases by one
+			 	 * third each third of its maximum speed spectrum.
+			 	 * Steam emission finally normalises at very
+				 * close to train's maximum speed (=GB(0,4)). */
+				if (GB(v->tick_counter, 0, (1 + ((u->cur_speed * 3) / u->tcache.cached_max_speed))) == 0) {
 					CreateEffectVehicleRel(v, x, y, 10, EV_STEAM_SMOKE);
 					sound = true;
 				}
 				break;
 
 			case 1:
-				/* diesel smoke */
-				if (u->cur_speed <= 40 && Chance16(15, 128)) {
+				/* Diesel smoke - thicker when train is starting, gradually
+				 * subsiding till locomotive reaches its maximum speed when it stops.
+				 * Details: Train's (max.) speed spectrum is divided into 32 parts.
+				 * When max. speed is reached, chance for smoke emission erodes by 32 (1/4).
+				 * Power and train's weight come in handy too to either increase smoke emission
+				 * in 6 steps (1000HP each) if the power is low or decrease smoke emission in
+				 * 6 steps (512 tonnes each) if the train isn't overweight. Power and weight
+				 * contributions are expressed in a way that neither extreme power, nor extreme
+				 * weight can ruin the balance (e.g. FreightWagonMultiplier) in the formula.
+				 * When the train reaches maximum speed no diesel_smoke is emitted as train
+				 * has enough traction to keep locomotive running optimally. */
+				if (u->cur_speed < u->tcache.cached_max_speed && Chance16((64 - ((u->cur_speed << 5) / u->tcache.cached_max_speed) + (32 >> (u->tcache.cached_power >> 10)) - (32 >> (u->tcache.cached_weight >> 9))), 128)) {
 					CreateEffectVehicleRel(v, 0, 0, 10, EV_DIESEL_SMOKE);
 					sound = true;
 				}
 				break;
 
 			case 2:
-				/* blue spark */
-				if (GB(v->tick_counter, 0, 2) == 0 && Chance16(1, 45)) {
+				/* Electric train's spark - more often occurs when train is departing (more load)
+				 * Details: Electric locomotives are usually at least twice as powerful as their diesel
+				 * counterparts, so spark emissions are kept simple. Only when starting, creating huge
+				 * force are sparks more likely to happen, but when reaching its max. speed, quarter by
+				 * quarter of it, chance decreases untill the usuall 2,22% at train's top speed. */
+				if (GB(v->tick_counter, 0, 2) == 0 && Chance16((6 - ((u->cur_speed << 2) / u->tcache.cached_max_speed)), 90)) {
 					CreateEffectVehicleRel(v, 0, 0, 10, EV_ELECTRIC_SPARK);
 					sound = true;
 				}