train.lua

local ipairs = ipairs

function find_access_tag(source,access_tags_hierarchy)
    for i,v in ipairs(access_tags_hierarchy) do
        local tag = source:get_value_by_key(v)
        if tag and tag ~= '' then
            return tag
        end
    end
    return ""
end

mainline_speed = 120
electrified_speed = 110
non_electrified_speed = 80
default_speed = 80
service_speed = 50

properties.traffic_signal_penalty        = 0
properties.u_turn_penalty                = 0
properties.use_turn_restrictions         = true
properties.continue_straight_at_waypoint = false

function way_function(way, result)
    local railway = way:get_value_by_key("railway")
    local service = way:get_value_by_key("service")
    local usage = way:get_value_by_key("usage")
    local maxspeed = way:get_value_by_key("maxspeed")
    local electrified = way:get_value_by_key("electrified")

    -- route only actual railways, no subways or disused pieces
    if (not railway or railway ~= 'rail') then
      return
    end

    result.forward_mode = mode.train
    result.backward_mode = mode.train

    result.type = 1
    result.name = 'rail'

    result.forward_speed = default_speed
    result.backward_speed = default_speed

    local maxspeed_as_number = 0
    if maxspeed then
      maxspeed_as_number = tonumber(maxspeed:match("%d*"))
      if maxspeed_as_number then
        if string.match(maxspeed, "mph") or string.match(maxspeed, "mp/h") then
          maxspeed_as_number = (maxspeed_as_number*1609)/1000
        end
      end
    end

    if maxspeed_as_number and maxspeed_as_number ~= 0 then
      result.forward_speed = maxspeed_as_number
      result.backward_speed = maxspeed_as_number
    elseif service then
      result.forward_speed = service_speed
      result.backward_speed = service_speed
    elseif (usage and usage == 'main') then
      result.forward_speed = mainline_speed
      result.backward_speed = mainline_speed
    elseif (electrified and electrified == "contact line") then
      result.forward_speed = electrified_speed
      result.backward_speed = electrified_speed
    elseif (electrified and electrified == "no") then
      result.forward_speed = non_electrified_speed
      result.backward_speed = non_electrified_speed
    else
      result.forward_speed = default_speed
      result.backward_speed = default_speed
    end

    return
end

function turn_function(angle)
  return (angle * 2)
  -- TODO permit angles more leniently in stations
end