diff --git a/activitysim/abm/models/atwork_subtour_scheduling.py b/activitysim/abm/models/atwork_subtour_scheduling.py
index 1fc66e4fe..8057d2c43 100644
--- a/activitysim/abm/models/atwork_subtour_scheduling.py
+++ b/activitysim/abm/models/atwork_subtour_scheduling.py
@@ -8,6 +8,7 @@
 import pandas as pd
 
 from activitysim.abm.models.util.vectorize_tour_scheduling import (
+    TourSchedulingSettings,
     vectorize_subtour_scheduling,
 )
 from activitysim.core import config, estimation, expressions, simulate
@@ -23,15 +24,6 @@
 DUMP = False
 
 
-class AtworkSubtourSchedulingSettings(PydanticReadable):
-    """
-    Settings for the `atwork_subtour_scheduling` component.
-    """
-
-    sharrow_skip: bool = True
-    """Skip Sharow"""  # TODO Check this again
-
-
 @workflow.step
 def atwork_subtour_scheduling(
     state: workflow.State,
@@ -39,7 +31,7 @@ def atwork_subtour_scheduling(
     persons_merged: pd.DataFrame,
     tdd_alts: pd.DataFrame,
     skim_dict: SkimDict | SkimDataset,
-    model_settings: AtworkSubtourSchedulingSettings | None = None,
+    model_settings: TourSchedulingSettings | None = None,
     model_settings_file_name: str = "tour_scheduling_atwork.yaml",
     trace_label: str = "atwork_subtour_scheduling",
 ) -> None:
@@ -56,7 +48,7 @@ def atwork_subtour_scheduling(
         return
 
     if model_settings is None:
-        model_settings = AtworkSubtourSchedulingSettings.read_settings_file(
+        model_settings = TourSchedulingSettings.read_settings_file(
             state.filesystem,
             model_settings_file_name,
         )
diff --git a/activitysim/abm/models/joint_tour_scheduling.py b/activitysim/abm/models/joint_tour_scheduling.py
index ae149c9dd..465b22b96 100644
--- a/activitysim/abm/models/joint_tour_scheduling.py
+++ b/activitysim/abm/models/joint_tour_scheduling.py
@@ -7,6 +7,7 @@
 import pandas as pd
 
 from activitysim.abm.models.util.vectorize_tour_scheduling import (
+    TourSchedulingSettings,
     vectorize_joint_tour_scheduling,
 )
 from activitysim.core import (
@@ -24,16 +25,17 @@
 logger = logging.getLogger(__name__)
 
 
-class JointTourSchedulingSettings(LogitComponentSettings, extra="forbid"):
-    """
-    Settings for the `joint_tour_scheduling` component.
-    """
-
-    preprocessor: PreprocessorSettings | None = None
-    """Setting for the preprocessor."""
-
-    sharrow_skip: bool = False
-    """Setting to skip sharrow"""
+# class JointTourSchedulingSettings(LogitComponentSettings, extra="forbid"):
+#     """
+#     Settings for the `joint_tour_scheduling` component.
+#     """
+#
+#     preprocessor: PreprocessorSettings | None = None
+#     """Setting for the preprocessor."""
+#
+#     sharrow_skip: bool = False
+#     """Setting to skip sharrow"""
+#
 
 
 @workflow.step
@@ -42,7 +44,7 @@ def joint_tour_scheduling(
     tours: pd.DataFrame,
     persons_merged: pd.DataFrame,
     tdd_alts: pd.DataFrame,
-    model_settings: JointTourSchedulingSettings | None = None,
+    model_settings: TourSchedulingSettings | None = None,
     model_settings_file_name: str = "joint_tour_scheduling.yaml",
     trace_label: str = "joint_tour_scheduling",
 ) -> None:
@@ -51,7 +53,7 @@ def joint_tour_scheduling(
     """
 
     if model_settings is None:
-        model_settings = JointTourSchedulingSettings.read_settings_file(
+        model_settings = TourSchedulingSettings.read_settings_file(
             state.filesystem,
             model_settings_file_name,
         )
diff --git a/activitysim/abm/models/stop_frequency.py b/activitysim/abm/models/stop_frequency.py
index 8d9789ac5..7e27ae08a 100644
--- a/activitysim/abm/models/stop_frequency.py
+++ b/activitysim/abm/models/stop_frequency.py
@@ -3,7 +3,8 @@
 from __future__ import annotations
 
 import logging
-from typing import Any
+from pathlib import Path
+from typing import Any, Literal
 
 import pandas as pd
 
@@ -24,20 +25,44 @@
 logger = logging.getLogger(__name__)
 
 
+class StopFrequencySpecSegmentSettings(LogitComponentSettings, extra="allow"):
+    # this class specifically allows "extra" settings because ActivitySim
+    # is set up to have the name of the segment column be identified with
+    # an arbitrary key.
+    SPEC: Path
+    COEFFICIENTS: Path
+
+
 class StopFrequencySettings(LogitComponentSettings, extra="forbid"):
     """
-    Settings for the `free_parking` component.
+    Settings for the stop frequency component.
+    """
+
+    LOGIT_TYPE: Literal["MNL"] = "MNL"
+    """Logit model mathematical form.
+
+    * "MNL"
+        Multinomial logit model.
     """
 
     preprocessor: PreprocessorSettings | None = None
     """Setting for the preprocessor."""
 
-    SPEC_SEGMENTS: dict[str, Any] = {}
-    # TODO Check this again
+    SPEC_SEGMENTS: list[StopFrequencySpecSegmentSettings] = {}
+
+    SPEC: Path | None = None
+    """Utility specification filename.
+
+    This is sometimes alternatively called the utility expressions calculator
+    (UEC). It is a CSV file giving all the functions for the terms of a
+    linear-in-parameters utility expression.  If SPEC_SEGMENTS is given, then
+    this unsegmented SPEC should be omitted.
+    """
 
     SEGMENT_COL: str = "primary_purpose"
 
-    # CONSTANTS TODO Check this again
+    CONSTANTS: dict[str, Any] = {}
+    """Named constants usable in the utility expressions."""
 
 
 @workflow.step
@@ -136,8 +161,7 @@ def stop_frequency(
 
     choices_list = []
     for segment_settings in spec_segments:
-        segment_name = segment_settings[segment_col]
-        segment_value = segment_settings[segment_col]
+        segment_name = segment_value = getattr(segment_settings, segment_col)
 
         chooser_segment = tours_merged[tours_merged[segment_col] == segment_value]
 
@@ -153,16 +177,14 @@ def stop_frequency(
             state, model_name=segment_name, bundle_name="stop_frequency"
         )
 
-        segment_spec = state.filesystem.read_model_spec(
-            file_name=segment_settings["SPEC"]
-        )
+        segment_spec = state.filesystem.read_model_spec(file_name=segment_settings.SPEC)
         assert segment_spec is not None, (
             "spec for segment_type %s not found" % segment_name
         )
 
-        coefficients_file_name = segment_settings["COEFFICIENTS"]
+        coefficients_file_name = segment_settings.COEFFICIENTS
         coefficients_df = state.filesystem.read_model_coefficients(
-            file_name=coefficients_file_name
+            file_name=str(coefficients_file_name)
         )
         segment_spec = simulate.eval_coefficients(
             state, segment_spec, coefficients_df, estimator
diff --git a/activitysim/abm/models/trip_scheduling.py b/activitysim/abm/models/trip_scheduling.py
index e9ddf96d0..c92cdb66c 100644
--- a/activitysim/abm/models/trip_scheduling.py
+++ b/activitysim/abm/models/trip_scheduling.py
@@ -5,6 +5,7 @@
 import logging
 import warnings
 from builtins import range
+from typing import List, Literal
 
 import numpy as np
 import pandas as pd
@@ -15,7 +16,7 @@
 )
 from activitysim.abm.models.util.trip import cleanup_failed_trips, failed_trip_cohorts
 from activitysim.core import chunk, config, estimation, expressions, tracing, workflow
-from activitysim.core.configuration.base import PydanticReadable
+from activitysim.core.configuration.base import PreprocessorSettings, PydanticReadable
 from activitysim.core.util import reindex
 
 logger = logging.getLogger(__name__)
@@ -41,18 +42,18 @@
 DEPARTURE_MODE = "departure"
 DURATION_MODE = "stop_duration"
 RELATIVE_MODE = "relative"
-PROBS_JOIN_COLUMNS_DEPARTURE_BASED = [
+PROBS_JOIN_COLUMNS_DEPARTURE_BASED: list[str] = [
     "primary_purpose",
     "outbound",
     "tour_hour",
     "trip_num",
 ]
-PROBS_JOIN_COLUMNS_DURATION_BASED = ["outbound", "stop_num"]
-PROBS_JOIN_COLUMNS_RELATIVE_BASED = ["outbound", "periods_left"]
+PROBS_JOIN_COLUMNS_DURATION_BASED: list[str] = ["outbound", "stop_num"]
+PROBS_JOIN_COLUMNS_RELATIVE_BASED: list[str] = ["outbound", "periods_left"]
 
 
-def _logic_version(model_settings):
-    logic_version = model_settings.get("logic_version", None)
+def _logic_version(model_settings: TripSchedulingSettings):
+    logic_version = model_settings.logic_version
     if logic_version is None:
         warnings.warn(
             "The trip_scheduling component now has a logic_version setting "
@@ -196,7 +197,7 @@ def schedule_trips_in_leg(
     outbound,
     trips,
     probs_spec,
-    model_settings,
+    model_settings: TripSchedulingSettings,
     is_last_iteration,
     trace_label,
     *,
@@ -220,29 +221,25 @@ def schedule_trips_in_leg(
         depart choice for trips, indexed by trip_id
     """
 
-    failfix = model_settings.get(FAILFIX, FAILFIX_DEFAULT)
-    depart_alt_base = model_settings.get("DEPART_ALT_BASE", 0)
-    scheduling_mode = model_settings.get("scheduling_mode", "departure")
-    preprocessor_settings = model_settings.get("preprocessor", None)
-
-    if scheduling_mode == "departure":
-        probs_join_cols = model_settings.get(
-            "probs_join_cols", PROBS_JOIN_COLUMNS_DEPARTURE_BASED
-        )
-    elif scheduling_mode == "stop_duration":
-        probs_join_cols = model_settings.get(
-            "probs_join_cols", PROBS_JOIN_COLUMNS_DURATION_BASED
-        )
-    elif scheduling_mode == "relative":
-        probs_join_cols = model_settings.get(
-            "probs_join_cols", PROBS_JOIN_COLUMNS_RELATIVE_BASED
-        )
-    else:
-        logger.error(
-            "Invalid scheduling mode specified: {0}.".format(scheduling_mode),
-            "Please select one of ['departure', 'stop_duration', 'relative'] and try again.",
-        )
-        raise ValueError(f"Invalid scheduling mode specified: {scheduling_mode}")
+    failfix = model_settings.FAILFIX
+    depart_alt_base = model_settings.DEPART_ALT_BASE
+    scheduling_mode = model_settings.scheduling_mode
+    preprocessor_settings = model_settings.preprocessor
+
+    probs_join_cols = model_settings.probs_join_cols
+    if probs_join_cols is None:
+        if scheduling_mode == "departure":
+            probs_join_cols = PROBS_JOIN_COLUMNS_DEPARTURE_BASED
+        elif scheduling_mode == "stop_duration":
+            probs_join_cols = PROBS_JOIN_COLUMNS_DURATION_BASED
+        elif scheduling_mode == "relative":
+            probs_join_cols = PROBS_JOIN_COLUMNS_RELATIVE_BASED
+        else:
+            logger.error(
+                "Invalid scheduling mode specified: {0}.".format(scheduling_mode),
+                "Please select one of ['departure', 'stop_duration', 'relative'] and try again.",
+            )
+            raise ValueError(f"Invalid scheduling mode specified: {scheduling_mode}")
 
     # logger.debug("%s scheduling %s trips" % (trace_label, trips.shape[0]))
 
@@ -451,6 +448,14 @@ class TripSchedulingSettings(PydanticReadable):
     """Integer to add to probs column index to get time period it represents.
     e.g. depart_alt_base = 5 means first column (column 0) represents 5 am"""
 
+    scheduling_mode: Literal["departure", "stop_duration", "relative"] = "departure"
+
+    probs_join_cols: list[str] | None = None
+
+    preprocessor: PreprocessorSettings | None = None
+
+    logic_version: int | None = None
+
 
 @workflow.step(copy_tables=False)
 def trip_scheduling(
@@ -560,7 +565,7 @@ def trip_scheduling(
         pd.Series(list(range(len(tours))), tours.index), trips_df.tour_id
     )
 
-    assert "DEPART_ALT_BASE" in model_settings
+    assert model_settings.DEPART_ALT_BASE
     failfix = model_settings.FAILFIX
 
     max_iterations = model_settings.MAX_ITERATIONS
@@ -609,9 +614,7 @@ def trip_scheduling(
                 failed = choices.reindex(trips_chunk.index).isnull()
                 logger.info("%s %s failed", trace_label_i, failed.sum())
 
-                if (failed.sum() > 0) & (
-                    model_settings.get("scheduling_mode") == "relative"
-                ):
+                if (failed.sum() > 0) & (model_settings.scheduling_mode == "relative"):
                     raise RuntimeError("failed trips with relative scheduling mode")
 
                 if not is_last_iteration:
diff --git a/activitysim/abm/models/util/tour_scheduling.py b/activitysim/abm/models/util/tour_scheduling.py
index bf69c6234..30a172a85 100644
--- a/activitysim/abm/models/util/tour_scheduling.py
+++ b/activitysim/abm/models/util/tour_scheduling.py
@@ -9,6 +9,8 @@
 from activitysim.abm.models.util import vectorize_tour_scheduling as vts
 from activitysim.core import config, estimation, expressions, simulate, workflow
 
+from .vectorize_tour_scheduling import TourModeComponentSettings, TourSchedulingSettings
+
 logger = logging.getLogger(__name__)
 
 
@@ -23,18 +25,26 @@ def run_tour_scheduling(
     trace_label = model_name
     model_settings_file_name = f"{model_name}.yaml"
 
-    model_settings = state.filesystem.read_model_settings(model_settings_file_name)
+    model_settings: TourSchedulingSettings = state.filesystem.read_settings_file(
+        model_settings_file_name,
+        mandatory=False,
+        validator_class=TourSchedulingSettings,
+    )
 
-    if "LOGSUM_SETTINGS" in model_settings:
-        logsum_settings = state.filesystem.read_model_settings(
-            model_settings["LOGSUM_SETTINGS"]
+    if model_settings.LOGSUM_SETTINGS:
+        logsum_settings: TourModeComponentSettings = (
+            state.filesystem.read_settings_file(
+                str(model_settings.LOGSUM_SETTINGS),
+                mandatory=False,
+                validator_class=TourModeComponentSettings,
+            )
         )
-        logsum_columns = logsum_settings.get("LOGSUM_CHOOSER_COLUMNS", [])
+        logsum_columns = logsum_settings.LOGSUM_CHOOSER_COLUMNS
     else:
         logsum_columns = []
 
     # - filter chooser columns for both logsums and simulate
-    model_columns = model_settings.get("SIMULATE_CHOOSER_COLUMNS", [])
+    model_columns = model_settings.SIMULATE_CHOOSER_COLUMNS
     chooser_columns = logsum_columns + [
         c for c in model_columns if c not in logsum_columns
     ]
@@ -44,7 +54,7 @@ def run_tour_scheduling(
     timetable = state.get_injectable("timetable")
 
     # - run preprocessor to annotate choosers
-    preprocessor_settings = model_settings.get("preprocessor", None)
+    preprocessor_settings = model_settings.preprocessor
     if preprocessor_settings:
         locals_d = {"tt": timetable.attach_state(state)}
         locals_d.update(config.get_model_constants(model_settings))
@@ -58,9 +68,9 @@ def run_tour_scheduling(
         )
 
     estimators = {}
-    if "TOUR_SPEC_SEGMENTS" in model_settings:
+    if model_settings.TOUR_SPEC_SEGMENTS:
         # load segmented specs
-        spec_segment_settings = model_settings.get("SPEC_SEGMENTS", {})
+        spec_segment_settings = model_settings.SPEC_SEGMENTS
         specs = {}
         sharrow_skips = {}
         for spec_segment_name, spec_settings in spec_segment_settings.items():
@@ -71,13 +81,13 @@ def run_tour_scheduling(
                 state, model_name=bundle_name, bundle_name=bundle_name
             )
 
-            spec_file_name = spec_settings["SPEC"]
+            spec_file_name = spec_settings.SPEC
             model_spec = state.filesystem.read_model_spec(file_name=spec_file_name)
             coefficients_df = state.filesystem.read_model_coefficients(spec_settings)
             specs[spec_segment_name] = simulate.eval_coefficients(
                 state, model_spec, coefficients_df, estimator
             )
-            sharrow_skips[spec_segment_name] = spec_settings.get("sharrow_skip", False)
+            sharrow_skips[spec_segment_name] = spec_settings.sharrow_skip
 
             if estimator:
                 estimators[spec_segment_name] = estimator  # add to local list
@@ -86,7 +96,7 @@ def run_tour_scheduling(
                 estimator.write_coefficients(coefficients_df, spec_settings)
 
         # - spec dict segmented by primary_purpose
-        tour_segment_settings = model_settings.get("TOUR_SPEC_SEGMENTS", {})
+        tour_segment_settings = model_settings.TOUR_SPEC_SEGMENTS
         tour_segments = {}
         for tour_segment_name, spec_segment_name in tour_segment_settings.items():
             tour_segments[tour_segment_name] = {}
@@ -105,15 +115,17 @@ def run_tour_scheduling(
 
     else:
         # unsegmented spec
-        assert "SPEC_SEGMENTS" not in model_settings
-        assert "TOUR_SPEC_SEGMENTS" not in model_settings
+        assert (
+            not model_settings.SPEC_SEGMENTS
+        ), f"model_settings.SPEC_SEGMENTS should be omitted not {model_settings.SPEC_SEGMENTS!r}"
+        assert not model_settings.TOUR_SPEC_SEGMENTS
         assert tour_segment_col is None
 
         estimator = estimation.manager.begin_estimation(state, model_name)
 
-        spec_file_name = model_settings["SPEC"]
+        spec_file_name = model_settings.SPEC
         model_spec = state.filesystem.read_model_spec(file_name=spec_file_name)
-        sharrow_skip = model_settings.get("sharrow_skip", False)
+        sharrow_skip = model_settings.sharrow_skip
         coefficients_df = state.filesystem.read_model_coefficients(model_settings)
         model_spec = simulate.eval_coefficients(
             state, model_spec, coefficients_df, estimator
diff --git a/activitysim/abm/models/util/vectorize_tour_scheduling.py b/activitysim/abm/models/util/vectorize_tour_scheduling.py
index b1701c309..88fd2dfd1 100644
--- a/activitysim/abm/models/util/vectorize_tour_scheduling.py
+++ b/activitysim/abm/models/util/vectorize_tour_scheduling.py
@@ -3,13 +3,18 @@
 from __future__ import annotations
 
 import logging
+from pathlib import Path
+from typing import Any
 
 import numpy as np
 import pandas as pd
 
+from activitysim.abm.models.tour_mode_choice import TourModeComponentSettings
 from activitysim.core import chunk, config, expressions, los, simulate
 from activitysim.core import timetable as tt
 from activitysim.core import tracing, workflow
+from activitysim.core.configuration.base import PreprocessorSettings, PydanticReadable
+from activitysim.core.configuration.logit import LogitComponentSettings
 from activitysim.core.interaction_sample_simulate import interaction_sample_simulate
 from activitysim.core.util import reindex
 
@@ -21,16 +26,52 @@
 RUN_ALTS_PREPROCESSOR_BEFORE_MERGE = True  # see FIXME below before changing this
 
 
-def skims_for_logsums(state: workflow.State, tour_purpose, model_settings, trace_label):
-    assert "LOGSUM_SETTINGS" in model_settings
+# class TourSchedulingSpecSegmentsSettings(PydanticReadable, extra="forbid"):
+#     COEFFICIENTS: Path
+#     SPEC: Path
 
+
+class TourSchedulingSettings(LogitComponentSettings, extra="forbid"):
+    LOGSUM_SETTINGS: Path | None = None
+    DESTINATION_FOR_TOUR_PURPOSE: str | dict[str, str] | None = None
+    LOGSUM_PREPROCESSOR: str = "preprocessor"
+    ALTS_PREPROCESSOR: PreprocessorSettings | dict[str, PreprocessorSettings] = {}
+    """
+    If the alternatives preprocessor is a single PreprocessorSettings object,
+    it is assumed to be an unsegmented preprocessor.  Otherwise, the dict keys
+    give the segements.
+    """
+    SIMULATE_CHOOSER_COLUMNS: list[str] | None = None
+    preprocessor: PreprocessorSettings | None = None
+    """Setting for the preprocessor."""
+
+    SPEC_SEGMENTS: dict[str, LogitComponentSettings] = {}
+
+    TOUR_SPEC_SEGMENTS: dict[str, str] = {}
+
+    SPEC: Path | None = None
+    """Utility specification filename.
+
+    This is sometimes alternatively called the utility expressions calculator
+    (UEC). It is a CSV file giving all the functions for the terms of a
+    linear-in-parameters utility expression.  If SPEC_SEGMENTS is given, then
+    this unsegmented SPEC should be omitted.
+    """
+
+
+def skims_for_logsums(
+    state: workflow.State,
+    tour_purpose,
+    model_settings: TourSchedulingSettings,
+    trace_label: str,
+):
     network_los = state.get_injectable("network_los")
 
     skim_dict = network_los.get_default_skim_dict()
 
     orig_col_name = "home_zone_id"
 
-    destination_for_tour_purpose = model_settings.get("DESTINATION_FOR_TOUR_PURPOSE")
+    destination_for_tour_purpose = model_settings.DESTINATION_FOR_TOUR_PURPOSE
     if isinstance(destination_for_tour_purpose, str):
         dest_col_name = destination_for_tour_purpose
     elif isinstance(destination_for_tour_purpose, dict):
@@ -97,7 +138,7 @@ def _compute_logsums(
     alt_tdd,
     tours_merged,
     tour_purpose,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     network_los,
     skims,
     trace_label,
@@ -109,8 +150,10 @@ def _compute_logsums(
     trace_label = tracing.extend_trace_label(trace_label, "logsums")
 
     with chunk.chunk_log(state, trace_label):
-        logsum_settings = state.filesystem.read_model_settings(
-            model_settings["LOGSUM_SETTINGS"]
+        logsum_settings = state.filesystem.read_settings_file(
+            str(model_settings.LOGSUM_SETTINGS),
+            mandatory=False,
+            validator_class=TourModeComponentSettings,
         )
         choosers = alt_tdd.join(tours_merged, how="left", rsuffix="_chooser")
         logger.info(
@@ -138,10 +181,7 @@ def _compute_logsums(
 
         # - run preprocessor to annotate choosers
         # allow specification of alternate preprocessor for nontour choosers
-        try:
-            preprocessor = model_settings.LOGSUM_PREPROCESSOR
-        except AttributeError:
-            preprocessor = model_settings.get("LOGSUM_PREPROCESSOR", "preprocessor")
+        preprocessor = model_settings.LOGSUM_PREPROCESSOR
         preprocessor_settings = (
             getattr(logsum_settings, preprocessor, None)
             or logsum_settings[preprocessor]
@@ -159,9 +199,7 @@ def _compute_logsums(
             )
 
         # - compute logsums
-        logsum_spec = state.filesystem.read_model_spec(
-            file_name=logsum_settings["SPEC"]
-        )
+        logsum_spec = state.filesystem.read_model_spec(file_name=logsum_settings.SPEC)
         logsum_spec = simulate.eval_coefficients(
             state, logsum_spec, coefficients, estimator=None
         )
@@ -309,7 +347,7 @@ def compute_tour_scheduling_logsums(
     alt_tdd,
     tours_merged,
     tour_purpose,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     skims,
     trace_label,
     *,
@@ -558,7 +596,12 @@ def tdd_interaction_dataset(
 
 
 def run_alts_preprocessor(
-    state: workflow.State, model_settings, alts, segment, locals_dict, trace_label
+    state: workflow.State,
+    model_settings: TourSchedulingSettings,
+    alts,
+    segment,
+    locals_dict,
+    trace_label,
 ):
     """
     run preprocessor on alts, as specified by ALTS_PREPROCESSOR in model_settings
@@ -583,18 +626,18 @@ def run_alts_preprocessor(
         annotated copy of alts
     """
 
-    preprocessor_settings = model_settings.get("ALTS_PREPROCESSOR", {})
+    preprocessor_settings = model_settings.ALTS_PREPROCESSOR
 
-    if segment in preprocessor_settings:
+    if isinstance(preprocessor_settings, dict) and segment in preprocessor_settings:
         # segmented by logsum_tour_purpose
         preprocessor_settings = preprocessor_settings.get(segment)
         logger.debug(
-            f"running ALTS_PREPROCESSOR with spec for {segment}: {preprocessor_settings.get('SPEC')}"
+            f"running ALTS_PREPROCESSOR with spec for {segment}: {preprocessor_settings.SPEC}"
         )
-    elif "SPEC" in preprocessor_settings:
+    elif isinstance(preprocessor_settings, PreprocessorSettings):
         # unsegmented (either because no segmentation, or fallback if settings has generic preprocessor)
         logger.debug(
-            f"running ALTS_PREPROCESSOR with unsegmented spec {preprocessor_settings.get('SPEC')}"
+            f"running ALTS_PREPROCESSOR with unsegmented spec {preprocessor_settings.SPEC}"
         )
     else:
         logger.debug(
@@ -626,7 +669,7 @@ def _schedule_tours(
     alts,
     spec,
     logsum_tour_purpose,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     skims,
     timetable,
     window_id_col,
@@ -661,7 +704,7 @@ def _schedule_tours(
         unavailable alternatives
     spec : DataFrame
         The spec which will be passed to interaction_simulate.
-    model_settings : dict
+    model_settings : TourSchedulingSettings
     timetable : TimeTable
         timetable of timewidows for person (or subtour) with rows for tours[window_id_col]
     window_id_col : str
@@ -811,7 +854,7 @@ def schedule_tours(
     alts,
     spec,
     logsum_tour_purpose,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     timetable,
     timetable_window_id_col,
     previous_tour,
@@ -846,7 +889,7 @@ def schedule_tours(
     else:
         assert not tours[timetable_window_id_col].duplicated().any()
 
-    if "LOGSUM_SETTINGS" in model_settings:
+    if model_settings.LOGSUM_SETTINGS:
         # we need skims to calculate tvpb skim overhead in 3_ZONE systems for use by calc_rows_per_chunk
         skims = skims_for_logsums(
             state, logsum_tour_purpose, model_settings, tour_trace_label
@@ -856,7 +899,7 @@ def schedule_tours(
 
     result_list = []
     for (
-        i,
+        _i,
         chooser_chunk,
         chunk_trace_label,
         chunk_sizer,
@@ -905,7 +948,7 @@ def vectorize_tour_scheduling(
     timetable,
     tour_segments,
     tour_segment_col,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     chunk_size=0,
     trace_label=None,
 ):
@@ -938,7 +981,7 @@ def vectorize_tour_scheduling(
     spec : DataFrame
         The spec which will be passed to interaction_simulate.
         (or dict of specs keyed on tour_type if tour_types is not None)
-    model_settings : dict
+    model_settings : LOGSUM_SETTINGS
 
     Returns
     -------
@@ -966,7 +1009,7 @@ def vectorize_tour_scheduling(
 
     timetable_window_id_col = "person_id"
     tour_owner_id_col = "person_id"
-    should_compute_logsums = "LOGSUM_SETTINGS" in model_settings
+    should_compute_logsums = model_settings.LOGSUM_SETTINGS is not None
 
     assert isinstance(tour_segments, dict)
 
@@ -1077,7 +1120,7 @@ def vectorize_subtour_scheduling(
     persons_merged,
     alts,
     spec,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     estimator,
     chunk_size=0,
     trace_label=None,
@@ -1107,7 +1150,7 @@ def vectorize_subtour_scheduling(
     spec : DataFrame
         The spec which will be passed to interaction_simulate.
         (all subtours share same spec regardless of subtour type)
-    model_settings : dict
+    model_settings : TourSchedulingSettings
     chunk_size
     trace_label
 
@@ -1207,7 +1250,7 @@ def build_joint_tour_timetables(
     joint_tour_windows_df = tt.create_timetable_windows(joint_tours, alts)
     joint_tour_timetable = tt.TimeTable(joint_tour_windows_df, alts)
 
-    for participant_num, nth_participants in joint_tour_participants.groupby(
+    for _participant_num, nth_participants in joint_tour_participants.groupby(
         "participant_num", sort=True
     ):
         # nth_participant windows from persons_timetable
@@ -1231,7 +1274,7 @@ def vectorize_joint_tour_scheduling(
     alts,
     persons_timetable,
     spec,
-    model_settings,
+    model_settings: TourSchedulingSettings,
     estimator,
     chunk_size=0,
     trace_label=None,
@@ -1257,7 +1300,7 @@ def vectorize_joint_tour_scheduling(
     spec : DataFrame
         The spec which will be passed to interaction_simulate.
         (or dict of specs keyed on tour_type if tour_types is not None)
-    model_settings : dict
+    model_settings : TourSchedulingSettings
 
     Returns
     -------
diff --git a/activitysim/core/configuration/logit.py b/activitysim/core/configuration/logit.py
index 96caf5150..c01187eeb 100644
--- a/activitysim/core/configuration/logit.py
+++ b/activitysim/core/configuration/logit.py
@@ -75,6 +75,9 @@ class BaseLogitComponentSettings(PydanticReadable):
     CONSTANTS: dict[str, Any] = {}
     """Named constants usable in the utility expressions."""
 
+    sharrow_skip: bool = False
+    """Skip sharrow when evaluating this component."""
+
 
 class LogitComponentSettings(BaseLogitComponentSettings):
     """
diff --git a/activitysim/core/simulate.py b/activitysim/core/simulate.py
index fc3f02c5e..f59e10839 100644
--- a/activitysim/core/simulate.py
+++ b/activitysim/core/simulate.py
@@ -27,6 +27,7 @@
 )
 from activitysim.core.configuration.base import PydanticBase
 from activitysim.core.configuration.logit import (
+    BaseLogitComponentSettings,
     LogitComponentSettings,
     LogitNestSpec,
     TemplatedLogitComponentSettings,
@@ -147,7 +148,7 @@ def read_model_spec(filesystem: configuration.FileSystem, file_name: Path | str)
 
 def read_model_coefficients(
     filesystem: configuration.FileSystem,
-    model_settings: LogitComponentSettings | dict[str, Any] | None = None,
+    model_settings: BaseLogitComponentSettings | dict[str, Any] | None = None,
     file_name: Path | str | None = None,
 ) -> pd.DataFrame:
     """
@@ -159,7 +160,7 @@ def read_model_coefficients(
         assert file_name is not None
     else:
         assert file_name is None
-        if isinstance(model_settings, LogitComponentSettings) or (
+        if isinstance(model_settings, BaseLogitComponentSettings) or (
             isinstance(model_settings, PydanticBase)
             and hasattr(model_settings, "COEFFICIENTS")
         ):