diff --git a/src/transport_performance/gtfs/multi_validation.py b/src/transport_performance/gtfs/multi_validation.py
index 518876e3..5d40c209 100644
--- a/src/transport_performance/gtfs/multi_validation.py
+++ b/src/transport_performance/gtfs/multi_validation.py
@@ -75,10 +75,8 @@ class MultiGtfsInstance:
         creates a calendar table from calendar_times.
     get_dates()
         Get the range of dates that the gtfs(s) span.
-    plot_routes()
-        Plot a timeseries of route counts.
-    plot_trips()
-        Plot a timeseries of trip counts.
+    plot_service()
+        Plot a timeseries of route or trip counts.
 
     Raises
     ------
@@ -738,7 +736,7 @@ def _reformat_col_names(self, col_name: str, cap_all: bool = True):
     def _plot_core(
         self,
         df: pd.DataFrame,
-        count_col: str = "trip_count",
+        service_type: str = "routes",
         width: int = 1000,
         height: int = 550,
         title: str = None,
@@ -749,13 +747,17 @@ def _plot_core(
         """Plot a timeseries for trip/route count."""
         # defences
         _type_defence(df, "df", pd.DataFrame)
-        _type_defence(count_col, "count_col", str)
+        # _type_defence(count_col, "count_col", str)
         _type_defence(width, "width", int)
         _type_defence(height, "height", int)
         _type_defence(title, "title", (str, type(None)))
         _type_defence(kwargs, "kwargs", dict)
         _type_defence(rolling_average, "rolling_average", (int, type(None)))
         _type_defence(line_date, "line_date", (str, type(None)))
+        if service_type == "routes":
+            count_col = "route_count"
+        else:
+            count_col = "trip_count"
         # preparation
         LABEL_FORMAT = {
             count_col: self._reformat_col_names(count_col),
@@ -804,8 +806,9 @@ def _plot_core(
 
         return fig
 
-    def plot_routes(
+    def plot_service(
         self,
+        service_type: str = "routes",
         route_type: bool = True,
         width: int = 1000,
         height: int = 550,
@@ -814,10 +817,12 @@ def plot_routes(
         rolling_average: Union[int, None] = None,
         line_date: Union[str, None] = None,
     ) -> go.Figure:
-        """Create a line plot of route counts over time.
+        """Create a line plot of route or trip counts over time.
 
         Parameters
         ----------
+        service_type: str, optional
+            Whether to plot 'routes' or 'trips'. By default 'routes'.
         route_type : bool, optional
             Whether or not to draw a line for each modality, by default True
         width : int, optional
@@ -846,82 +851,22 @@ def plot_routes(
 
         """
         # defences
+        _type_defence(service_type, "service_type", str)
         _type_defence(route_type, "route_type", bool)
         _type_defence(plotly_kwargs, "plotly_kwargs", (dict, type(None)))
         if not plotly_kwargs:
             plotly_kwargs = {}
-        # prepare data
-        data = self.summarise_routes().copy()
-        if not route_type:
-            data = (
-                data.drop("route_type", axis=1)
-                .groupby("date")
-                .sum()
-                .reset_index()
+        SERVICE_TYPES = ["routes", "trips"]
+        if service_type not in SERVICE_TYPES:
+            raise ValueError(
+                "`service_type` expects 'routes' or 'trips',"
+                f" found: {service_type}"
             )
-        figure = self._plot_core(
-            data,
-            "route_count",
-            width=width,
-            height=height,
-            title=title,
-            kwargs=plotly_kwargs,
-            rolling_average=rolling_average,
-            line_date=line_date,
-        )
-        return figure
-
-    def plot_trips(
-        self,
-        route_type: bool = True,
-        width: int = 1000,
-        height: int = 550,
-        title: str = None,
-        plotly_kwargs: dict = None,
-        rolling_average: Union[int, None] = None,
-        line_date: Union[str, None] = None,
-    ) -> go.Figure:
-        """Create a line plot of trip counts over time.
-
-        Parameters
-        ----------
-        route_type : bool, optional
-            Whether or not to draw a line for each modality, by default True
-        width : int, optional
-            Plot width, by default 1000
-        height : int, optional
-            Plot height, by default 550
-        title : str, optional
-            Plot title, by default None
-        plotly_kwargs : dict, optional
-            Kwargs to pass to plotly.express.line, by default None
-        rolling_average : Union[int, None], optional
-            How many days to calculate the rolling average over. When left as
-            None, rolling average is not used.
-            The rolling average is calculated from the center, meaning if ra=3,
-            the average will be calculated from the current date, previous date
-            and following date. Missing dates are imputed and treated as having
-            values of 0.
-        line_date : Union[str, None], optional
-            A data to draw a dashed vertical line on. Date should be in format:
-            YYYY-MM-DD, by default None
-
-        Returns
-        -------
-        go.Figure
-            The timerseries plot
+        if service_type == "routes":
+            data = self.summarise_routes().copy()
+        else:
+            data = self.summarise_trips().copy()
 
-        """
-        # NOTE: Very similar to the above function, however not enough code
-        # to justify creating a shared function (would probably results in a
-        # similar amount)
-        # defences
-        _type_defence(route_type, "route_type", bool)
-        _type_defence(plotly_kwargs, "plotly_kwargs", (dict, type(None)))
-        if not plotly_kwargs:
-            plotly_kwargs = {}
-        # prepare data
-        data = self.summarise_trips().copy()
         if not route_type:
             data = (
                 data.drop("route_type", axis=1)
@@ -931,7 +876,7 @@ def plot_trips(
             )
         figure = self._plot_core(
             data,
-            "trip_count",
+            service_type=service_type,
             width=width,
             height=height,
             title=title,