index.js

const segments = (state = {}, action) => {
  switch (action.type) {
    case actions.LOAD_SEGMENTS:
      return {
        ...state,
        segments: action.segments
          .map(segments => segments.values_)
          .reduce((result, item) => {     
            result[item.highway] = result[item.highway] || {};
            result[item.highway][item.district] = result[item.highway][item.district] || {};
            result[item.highway][item.district][item.segment] = item;
            return result;
          }, {}),
      }
    default:
      return state;
  }
};