This lua file is used in OSRM v5.23.0 and makes use of polygons provided to manipulate the edge forward and backward speed. Look for "customized speed manipulation" in the lua script.

car-location-dependent-speeds.lua

api_version = 4

Set = require('lib/set')
Sequence = require('lib/sequence')
Handlers = require("lib/way_handlers")
Relations = require("lib/relations")
find_access_tag = require("lib/access").find_access_tag
limit = require("lib/maxspeed").limit
Utils = require("lib/utils")
Measure = require("lib/measure")

function setup()
  return {
    properties = {
      max_speed_for_map_matching      = 180/3.6, -- 180kmph -> m/s
      -- For routing based on duration, but weighted for preferring certain roads
      weight_name                     = 'routability',
      -- For shortest duration without penalties for accessibility
      -- weight_name                     = 'duration',
      -- For shortest distance without penalties for accessibility
      -- weight_name                     = 'distance',
      process_call_tagless_node      = false,
      u_turn_penalty                 = 20,
      continue_straight_at_waypoint  = true,
      use_turn_restrictions          = true,
      left_hand_driving              = false,
      traffic_light_penalty          = 2,
    },

    default_mode              = mode.driving,
    default_speed             = 10,
    oneway_handling           = true,
    side_road_multiplier      = 0.8,
    turn_penalty              = 7.5,
    speed_reduction           = 0.8,
    turn_bias                 = 1.075,
    cardinal_directions       = false,

    -- Size of the vehicle, to be limited by physical restriction of the way
    vehicle_height = 2.0, -- in meters, 2.0m is the height slightly above biggest SUVs
    vehicle_width = 1.9, -- in meters, ways with narrow tag are considered narrower than 2.2m

    -- Size of the vehicle, to be limited mostly by legal restriction of the way
    vehicle_length = 4.8, -- in meters, 4.8m is the length of large or family car
    vehicle_weight = 2000, -- in kilograms

    -- a list of suffixes to suppress in name change instructions. The suffixes also include common substrings of each other
    suffix_list = {
      'N', 'NE', 'E', 'SE', 'S', 'SW', 'W', 'NW', 'North', 'South', 'West', 'East', 'Nor', 'Sou', 'We', 'Ea'
    },

    barrier_whitelist = Set {
      'cattle_grid',
      'border_control',
      'toll_booth',
      'sally_port',
      'gate',
      'lift_gate',
      'no',
      'entrance',
      'height_restrictor',
      'arch'
    },

    access_tag_whitelist = Set {
      'yes',
      'motorcar',
      'motor_vehicle',
      'vehicle',
      'permissive',
      'designated',
      'hov'
    },

    access_tag_blacklist = Set {
      'no',
      'agricultural',
      'forestry',
      'emergency',
      'psv',
      'customers',
      'private',
      'delivery',
      'destination'
    },

    -- tags disallow access to in combination with highway=service
    service_access_tag_blacklist = Set {
        'private'
    },

    restricted_access_tag_list = Set {
      'private',
      'delivery',
      'destination',
      'customers',
    },

    access_tags_hierarchy = Sequence {
      'motorcar',
      'motor_vehicle',
      'vehicle',
      'access'
    },

    service_tag_forbidden = Set {
      'emergency_access'
    },

    restrictions = Sequence {
      'motorcar',
      'motor_vehicle',
      'vehicle'
    },

    classes = Sequence {
        'toll', 'motorway', 'ferry', 'restricted', 'tunnel'
    },

    -- classes to support for exclude flags
    excludable = Sequence {
        Set {'toll'},
        Set {'motorway'},
        Set {'ferry'}
    },

    avoid = Set {
      'area',
      -- 'toll',    -- uncomment this to avoid tolls
      'reversible',
      'impassable',
      'hov_lanes',
      'steps',
      'construction',
      'proposed'
    },

    speeds = Sequence {
      highway = {
        motorway        = 90,
        motorway_link   = 45,
        trunk           = 85,
        trunk_link      = 40,
        primary         = 65,
        primary_link    = 30,
        secondary       = 55,
        secondary_link  = 25,
        tertiary        = 40,
        tertiary_link   = 20,
        unclassified    = 25,
        residential     = 25,
        living_street   = 10,
        service         = 15
      }
    },

    service_penalties = {
      alley             = 0.5,
      parking           = 0.5,
      parking_aisle     = 0.5,
      driveway          = 0.5,
      ["drive-through"] = 0.5,
      ["drive-thru"] = 0.5
    },

    restricted_highway_whitelist = Set {
      'motorway',
      'motorway_link',
      'trunk',
      'trunk_link',
      'primary',
      'primary_link',
      'secondary',
      'secondary_link',
      'tertiary',
      'tertiary_link',
      'residential',
      'living_street',
      'unclassified',
      'service'
    },

    construction_whitelist = Set {
      'no',
      'widening',
      'minor',
    },

    route_speeds = {
      ferry = 5,
      shuttle_train = 10
    },

    bridge_speeds = {
      movable = 5
    },

    -- surface/trackype/smoothness
    -- values were estimated from looking at the photos at the relevant wiki pages

    -- max speed for surfaces
    surface_speeds = {
      asphalt = nil,    -- nil mean no limit. removing the line has the same effect
      concrete = nil,
      ["concrete:plates"] = nil,
      ["concrete:lanes"] = nil,
      paved = nil,

      cement = 80,
      compacted = 80,
      fine_gravel = 80,

      paving_stones = 60,
      metal = 60,
      bricks = 60,

      grass = 40,
      wood = 40,
      sett = 40,
      grass_paver = 40,
      gravel = 40,
      unpaved = 40,
      ground = 40,
      dirt = 40,
      pebblestone = 40,
      tartan = 40,

      cobblestone = 30,
      clay = 30,

      earth = 20,
      stone = 20,
      rocky = 20,
      sand = 20,

      mud = 10
    },

    -- max speed for tracktypes
    tracktype_speeds = {
      grade1 =  60,
      grade2 =  40,
      grade3 =  30,
      grade4 =  25,
      grade5 =  20
    },

    -- max speed for smoothnesses
    smoothness_speeds = {
      intermediate    =  80,
      bad             =  40,
      very_bad        =  20,
      horrible        =  10,
      very_horrible   =  5,
      impassable      =  0
    },

    -- http://wiki.openstreetmap.org/wiki/Speed_limits
    maxspeed_table_default = {
      urban = 50,
      rural = 90,
      trunk = 110,
      motorway = 130
    },

    -- List only exceptions
    maxspeed_table = {
      ["at:rural"] = 100,
      ["at:trunk"] = 100,
      ["be:motorway"] = 120,
      ["be-vlg:rural"] = 70,
      ["by:urban"] = 60,
      ["by:motorway"] = 110,
      ["ch:rural"] = 80,
      ["ch:trunk"] = 100,
      ["ch:motorway"] = 120,
      ["cz:trunk"] = 0,
      ["cz:motorway"] = 0,
      ["de:living_street"] = 7,
      ["de:rural"] = 100,
      ["de:motorway"] = 0,
      ["dk:rural"] = 80,
      ["fr:rural"] = 80,
      ["gb:nsl_single"] = (60*1609)/1000,
      ["gb:nsl_dual"] = (70*1609)/1000,
      ["gb:motorway"] = (70*1609)/1000,
      ["nl:rural"] = 80,
      ["nl:trunk"] = 100,
      ['no:rural'] = 80,
      ['no:motorway'] = 110,
      ['pl:rural'] = 100,
      ['pl:trunk'] = 120,
      ['pl:motorway'] = 140,
      ["ro:trunk"] = 100,
      ["ru:living_street"] = 20,
      ["ru:urban"] = 60,
      ["ru:motorway"] = 110,
      ["uk:nsl_single"] = (60*1609)/1000,
      ["uk:nsl_dual"] = (70*1609)/1000,
      ["uk:motorway"] = (70*1609)/1000,
      ['za:urban'] = 60,
      ['za:rural'] = 100,
      ["none"] = 140
    },

    relation_types = Sequence {
      "route"
    },

    -- classify highway tags when necessary for turn weights
    highway_turn_classification = {
    },

    -- classify access tags when necessary for turn weights
    access_turn_classification = {
    }
  }
end

function process_node(profile, node, result, relations)
  -- parse access and barrier tags
  local access = find_access_tag(node, profile.access_tags_hierarchy)
  if access then
    if profile.access_tag_blacklist[access] and not profile.restricted_access_tag_list[access] then
      result.barrier = true
    end
  else
    local barrier = node:get_value_by_key("barrier")
    if barrier then
      --  check height restriction barriers
      local restricted_by_height = false
      if barrier == 'height_restrictor' then
         local maxheight = Measure.get_max_height(node:get_value_by_key("maxheight"), node)
         restricted_by_height = maxheight and maxheight < profile.vehicle_height
      end

      --  make an exception for rising bollard barriers
      local bollard = node:get_value_by_key("bollard")
      local rising_bollard = bollard and "rising" == bollard

      if not profile.barrier_whitelist[barrier] and not rising_bollard or restricted_by_height then
        result.barrier = true
      end
    end
  end

  -- check if node is a traffic light
  local tag = node:get_value_by_key("highway")
  if "traffic_signals" == tag then
    result.traffic_lights = true
  end
end

function process_way(profile, way, result, relations)
  -- the intial filtering of ways based on presence of tags
  -- affects processing times significantly, because all ways
  -- have to be checked.
  -- to increase performance, prefetching and intial tag check
  -- is done in directly instead of via a handler.

  -- in general we should  try to abort as soon as
  -- possible if the way is not routable, to avoid doing
  -- unnecessary work. this implies we should check things that
  -- commonly forbids access early, and handle edge cases later.

  -- data table for storing intermediate values during processing
  local data = {
    -- prefetch tags
    highway = way:get_value_by_key('highway'),
    bridge = way:get_value_by_key('bridge'),
    route = way:get_value_by_key('route')
  }

  -- perform an quick initial check and abort if the way is
  -- obviously not routable.
  -- highway or route tags must be in data table, bridge is optional
  if (not data.highway or data.highway == '') and
  (not data.route or data.route == '')
  then
    return
  end

  handlers = Sequence {
    -- set the default mode for this profile. if can be changed later
    -- in case it turns we're e.g. on a ferry
    WayHandlers.default_mode,

    -- check various tags that could indicate that the way is not
    -- routable. this includes things like status=impassable,
    -- toll=yes and oneway=reversible
    WayHandlers.blocked_ways,
    WayHandlers.avoid_ways,
    WayHandlers.handle_height,
    WayHandlers.handle_width,
    WayHandlers.handle_length,
    WayHandlers.handle_weight,

    -- determine access status by checking our hierarchy of
    -- access tags, e.g: motorcar, motor_vehicle, vehicle
    WayHandlers.access,

    -- check whether forward/backward directions are routable
    WayHandlers.oneway,

    -- check a road's destination
    WayHandlers.destinations,

    -- check whether we're using a special transport mode
    WayHandlers.ferries,
    WayHandlers.movables,

    -- handle service road restrictions
    WayHandlers.service,

    -- handle hov
    WayHandlers.hov,

    -- compute speed taking into account way type, maxspeed tags, etc.
    WayHandlers.speed,
    WayHandlers.surface,
    WayHandlers.maxspeed,
    WayHandlers.penalties,

    -- compute class labels
    WayHandlers.classes,

    -- handle turn lanes and road classification, used for guidance
    WayHandlers.turn_lanes,
    WayHandlers.classification,

    -- handle various other flags
    WayHandlers.roundabouts,
    WayHandlers.startpoint,
    WayHandlers.driving_side,

    -- set name, ref and pronunciation
    WayHandlers.names,

    -- set weight properties of the way
    WayHandlers.weights,

    -- set classification of ways relevant for turns
    WayHandlers.way_classification_for_turn
  }

  WayHandlers.run(profile, way, result, data, handlers, relations)

  -- customized speed manipulation 
  forward_sp = result.forward_speed
  backward_sp = result.backward_speed

  factor = 1.0
  if way:get_location_tag('speed_factor') then
    factor = way:get_location_tag('speed_factor')
  end

  if forward_sp and forward_sp > 0 then
    result.forward_speed = forward_sp * factor
  end

  if backward_sp and backward_sp > 0 then
    result.backward_speed = backward_sp * factor
  end
  -- end customized speed manipulation

  if profile.cardinal_directions then
      Relations.process_way_refs(way, relations, result)
  end
end

function process_turn(profile, turn)
  -- Use a sigmoid function to return a penalty that maxes out at turn_penalty
  -- over the space of 0-180 degrees.  Values here were chosen by fitting
  -- the function to some turn penalty samples from real driving.
  local turn_penalty = profile.turn_penalty
  local turn_bias = turn.is_left_hand_driving and 1. / profile.turn_bias or profile.turn_bias

  if turn.has_traffic_light then
      turn.duration = profile.properties.traffic_light_penalty
  end

  if turn.number_of_roads > 2 or turn.source_mode ~= turn.target_mode or turn.is_u_turn then
    if turn.angle >= 0 then
      turn.duration = turn.duration + turn_penalty / (1 + math.exp( -((13 / turn_bias) *  turn.angle/180 - 6.5*turn_bias)))
    else
      turn.duration = turn.duration + turn_penalty / (1 + math.exp( -((13 * turn_bias) * -turn.angle/180 - 6.5/turn_bias)))
    end

    if turn.is_u_turn then
      turn.duration = turn.duration + profile.properties.u_turn_penalty
    end
  end

  -- for distance based routing we don't want to have penalties based on turn angle
  if profile.properties.weight_name == 'distance' then
     turn.weight = 0
  else
     turn.weight = turn.duration
  end

  if profile.properties.weight_name == 'routability' then
      -- penalize turns from non-local access only segments onto local access only tags
      if not turn.source_restricted and turn.target_restricted then
          turn.weight = constants.max_turn_weight
      end
  end
end

return {
  setup = setup,
  process_way = process_way,
  process_node = process_node,
  process_turn = process_turn
}

I don't think so, possibly a MultiPolygon will work but that then would use the same settings for all polygons within. Just give it a try, you will find eventually out :-)

Thanks! In that case it wouldnt be that bad. I could just have two sequential multipolygon jsons, one with each new speeds according to the two different depths im considering.

I cant wait to dive in! Thank you for your help. I am 0 familiar with lua so if there is an editor or viewer I should seek, any link to a set up tutorial / osm lua files handling tutorial would be amazing. Will report back if I have results.

Reg. the lua files, there are many flying around as gists and there is quite some information in the repo itself, you will have to browse around a bit. Printing within the lua file is usually my best friend. If Multipolygon does not work, you would also "script together" the CLI command if there are hundreds of location data arguments.