diff --git a/makefile b/makefile
index cdb5703..7e6d949 100644
--- a/makefile
+++ b/makefile
@@ -127,6 +127,8 @@ data/gtfs/%.merged.with_flex.gtfs: data/gtfs/%.merged.gtfs.zip
 	$(info patching GTFS-Flex data into the GTFS feed)
 	# todo: pick flex rules file based on GTFS feed
 	docker run -i --rm -v $(HOST_MOUNT)/data/gtfs/$(@F):/gtfs derhuerst/generate-gtfs-flex:4 stadtnavi-herrenberg-flex-rules.js
+	$(info generating emissions.txt)
+	python3 scripts/generate_emissions_file.py $@  
 
 data/gtfs/%.merged.with_flex.gtfs.zip: data/gtfs/%.merged.with_flex.gtfs
 	rm -f $@
diff --git a/scripts/generate_emissions_file.py b/scripts/generate_emissions_file.py
new file mode 100644
index 0000000..9c9058b
--- /dev/null
+++ b/scripts/generate_emissions_file.py
@@ -0,0 +1,102 @@
+import csv
+import sys
+from argparse import ArgumentParser
+from pathlib import Path
+
+emissions_per_route_type = {
+    3: {"avg_co2_per_vehicle_per_km": 85, "avg_passenger_count": 1}, # Bus
+    0: {"avg_co2_per_vehicle_per_km": 37.7, "avg_passenger_count": 1}, # Interpretiere Tram, Streetcar, Light rail wie S-Bahn
+    109: {"avg_co2_per_vehicle_per_km": 37.7, "avg_passenger_count": 1}, # S-Bahn
+    2: {"avg_co2_per_vehicle_per_km": 54, "avg_passenger_count": 1}, # Intepretiere Rails (Long Distance) wie Regionalbahn
+    106: {"avg_co2_per_vehicle_per_km": 54, "avg_passenger_count": 1}, # Regionalbahn
+    1: {"avg_co2_per_vehicle_per_km": 2.6, "avg_passenger_count": 1}, # interpretiere Subway, Metro wie Stadtbahn
+    403: {"avg_co2_per_vehicle_per_km": 2.6, "avg_passenger_count": 1}, # Stadtbahn
+    4: {"avg_co2_per_vehicle_per_km": 2600, "avg_passenger_count": 1.4}, # Ferries
+    7: {"avg_co2_per_vehicle_per_km": 2.6, "avg_passenger_count": 1}, # Funicular, Übernahme Wert Stadtbahn
+}
+
+# Estimating CO2 emissions for funiculars:
+# VVS does not provide numbers neither for Seilbahn ("Außerhalb Tarifgebiet") 
+# nor Zahnradbahn ("1.2km Fußweg (while it's 2.4km [1] or 1.6 fly distance)")
+# We assume it is approximately the Stadtbahn. 
+# [1] https://herrenberg.stadtnavi.de/reiseplan/Marienplatz%2C%20Stuttgart%3A%3A48.7642519%2C9.1681266/Degerloch%2C%20Stuttgart%3A%3A48.7485636%2C9.1682656/walk?time=1731217647
+
+# Estimating CO2 emissions for ferries:
+# CO2 emissions for ferries are barely available. We deduced them from a single datapoint
+# we found: 2.8l per car for the Horgener Zürichsee-Ferry [1]. As the distance between Horgen
+# and Meilen is, according to OSM exactly 2.8km, we assume it's 1l/km. As 1l Diesel
+# corresponds to 2.6kg CO2 [3], that corresponds to 1l/PKWkm*2600g => 2600g/km. 
+# Per car we assume a medium occupancy of 1.4
+# [1] https://www.tagesanzeiger.ch/die-faehre-verbraucht-einen-liter-fuer-2-8-kilometer-pro-auto-737265054748
+# [2] https://www.openstreetmap.org/directions?engine=graphhopper_foot&route=47.25919%2C8.60453%3B47.26770%2C8.63839
+# [3] https://www.econologie.de/Emissions-co2-Liter-Kraftstoff-Benzin-oder-Diesel-gpl/
+
+
+
+def eprint(*args, **kwargs):
+    print(*args, file=sys.stderr, **kwargs)
+
+def map_to_standard_route_type(extended_route_type: int) -> int:
+    if extended_route_type < 15:
+        return extended_route_type
+    if extended_route_type >= 400 and extended_route_type < 500:
+        return 1
+    if extended_route_type >= 100 and extended_route_type < 200:
+        return 2
+    if extended_route_type >= 700 and extended_route_type < 800:
+        return 3
+    if extended_route_type >= 1400 and extended_route_type < 1500:
+        return 7
+    eprint(f"WARN: no mapping to standard route_type for {extended_route_type}")
+    return extended_route_type    
+
+def print_mappings(used_route_types: set[int]):
+    eprint("The following co2 emissions per route type where used:")
+    eprint(f'route_type|avg_co2_per_vehicle_per_km|avg_passenger_count')
+    eprint(f'----------|--------------------------|-------------------')
+    
+    for route_type in used_route_types:
+        mapped_route_type = map_to_standard_route_type(route_type)
+        emissions = emissions_per_route_type[mapped_route_type]
+        avg_co2_per_vehicle_per_km = emissions['avg_co2_per_vehicle_per_km']
+        avg_passenger_count = emissions['avg_passenger_count']
+        eprint(f'{route_type: 10}|{avg_co2_per_vehicle_per_km: 26}|{avg_passenger_count: 19}')
+
+def generate_emissions_file(routes_file_path: str, emissions_file_path: str) -> None:
+    used_route_types = set()
+    with open(routes_file_path) as f:
+        reader = csv.DictReader(f)
+
+        emissions = []
+        for route in reader:
+            route_type = int(route["route_type"])
+            used_route_types.add(route_type)
+            standard_route_type = map_to_standard_route_type(route_type)
+            route_id = route["route_id"]
+            route_type_emissions = emissions_per_route_type.get(route_type, emissions_per_route_type.get(standard_route_type))
+            if not route_type_emissions:
+                eprint(f"Error: no emissions defined for route_type {route_type} or route {route_id}")
+            else:
+                route_emission= {}
+                route_emission["route_id"] = route_id
+                route_emission["avg_co2_per_vehicle_per_km"] = route_type_emissions['avg_co2_per_vehicle_per_km']
+                route_emission["avg_passenger_count"] = route_type_emissions['avg_passenger_count']
+                emissions.append(route_emission)
+
+    with open(emissions_file_path, 'w') as f:
+        fieldnames = ['route_id', 'avg_co2_per_vehicle_per_km', 'avg_passenger_count' ]
+        writer = csv.DictWriter(f, fieldnames=fieldnames)
+        
+        writer.writeheader()
+        for route_emisions in emissions:
+            writer.writerow(route_emisions)
+
+    print_mappings(used_route_types)
+
+if __name__ == "__main__":
+    parser = ArgumentParser(prog='generate_emissions_file')
+    parser.add_argument('gtfs_dir', help='Path to GTFS directory')
+    args = parser.parse_args()
+    generate_emissions_file(Path(args.gtfs_dir, 'routes.txt'), Path(args.gtfs_dir, 'emissions.txt'))
+
+    
\ No newline at end of file