Предлагаемое изменение в слое bridge (https://github.com/mapbox/osm-bright/blob/master/osm-bright/osm-bright.osm2pgsql.mml#L392)

bridge_new.sql

  SELECT way, COALESCE(p_o_l.highway, p_o_l.railway) AS "type", 1 AS bridge, access, render.render, layer, 0 as tunnel,
  COALESCE(hw.stylegroup, constr.stylegroup, rw.stylegroup, 'other') AS stylegroup
  FROM planet_osm_line as p_o_l
  INNER JOIN (values
        ('1_outline')
  ,     ('2_line')
  ,     ('3_inline')
  ) AS render (render) ON 1=1
  LEFT JOIN (values
        ('motorway', 'motorway')
  ,     ('trunk', 'motorway')
  ,     ('primary', 'mainroad')
  ,     ('secondary', 'mainroad')
  ,     ('motorway_link', 'minorroad')
  ,     ('trunk_link', 'minorroad')
  ,     ('primary_link', 'minorroad')
  ,     ('secondary_link', 'minorroad')
  ,     ('tertiary', 'minorroad')
  ,     ('tertiary_link', 'minorroad')
  ,     ('residential', 'minorroad')
  ,     ('unclassified', 'minorroad')
  ,     ('road', 'minorroad')
  ,     ('living_street', 'minorroad')
  ,     ('service', 'service')
  ,     ('track', 'service')
  ,     ('path', 'noauto')
  ,     ('cycleway', 'noauto')
  ,     ('footway', 'noauto')
  ,     ('pedestrian', 'noauto')
  ,     ('steps', 'noauto')
  ,     ('bridleway', 'noauto')
  ) as hw (k, stylegroup) ON hw.k = p_o_l.highway
  LEFT JOIN (values
        ('tertiary', 'construction')
  ,     ('motorway', 'construction')
  ,     ('trunk', 'construction')
  ,     ('unclassified', 'construction')
  ,     ('primary', 'construction')
  ,     ('motorway_link', 'construction')
  ,     ('secondary', 'construction')
  ,     ('residential', 'construction')
  ,     ('trunk_link', 'construction')                                                                                                                                                                           
  ) as constr (k, stylegroup) ON constr.k = p_o_l.construction
  LEFT JOIN (values
        ('light_rail', 'railway')
  ,     ('subway', 'railway')
  ,     ('narrow_gauge', 'railway')
  ,     ('rail', 'railway')
  ,     ('tram', 'railway')
  ) as rw (k, stylegroup) ON rw.k = p_o_l.railway
  WHERE p_o_l.bridge NOT IN ('', '0', 'no')
  AND "way" && ST_SetSRID('BOX3D(14861804.28355137 3903791.908582617,15037915.19672051 4079902.821751758)'::box3d, 3857)
  ORDER BY layer ASC, render ASC;

bridge_old.sql

 SELECT way, COALESCE(construction, highway, railway) AS "type", 1 AS bridge, access, render, layer, 0 as tunnel,
  CASE
    WHEN construction IN ('tertiary','motorway','trunk','unclassified','primary','motorway_link','secondary','residential','trunk_link') THEN 'construction'
    WHEN highway IN ('motorway', 'trunk') THEN 'motorway' 
    WHEN highway IN ('primary', 'secondary') THEN 'mainroad'
    WHEN highway IN ('motorway_link', 'trunk_link', 'primary_link', 'secondary_link', 'tertiary', 'tertiary_link', 'residential', 'unclassified', 'road', 'living_street') THEN 'minorroad'
    WHEN highway IN ('service', 'track') THEN 'service'
    WHEN highway IN ('path', 'cycleway', 'footway', 'pedestrian', 'steps', 'bridleway') THEN 'noauto'
    WHEN railway IN ('light_rail', 'subway', 'narrow_gauge', 'rail', 'tram') THEN 'railway'
    ELSE 'other'
  END AS stylegroup
 FROM (
    SELECT *, '1_outline' AS render FROM planet_osm_line WHERE bridge NOT IN ('', '0', 'no')
    UNION ALL
    SELECT *, '2_line' AS render FROM planet_osm_line WHERE bridge NOT IN ('', '0', 'no')
    UNION ALL
    SELECT *, '3_inline' AS render FROM planet_osm_line WHERE bridge NOT IN ('', '0', 'no')
 ) AS bridges
WHERE "way" && ST_SetSRID('BOX3D(14861804.28355137 3903791.908582617,15037915.19672051 4079902.821751758)'::box3d, 3857)
 ORDER BY layer ASC, render ASC;