Ask Your Mates Open Forum

Road Segmentation

  • 1.  Road Segmentation

    Posted 12 February 2019 16:38
    I am installing a new AM system and taking the opportunity to change the way things are recorded. This issue has had me in a quandary for some time. Do you segment the road between:
    1. All intersections (regardless)
    2. Most intersections (using a sensible minimum length for a segment), or
    3. Only between crossroads (applying a reasonable length rule for long sections)
    The caveat being for really long sections, use a fixed geographic point such as a bridge or sharp bend, railway or "T" intersection.  (not a gate post) such as long country roads
    4. Case by case method, deciding as you go.

    I realise that the rule wouldn't be fixed hard and there will always be exceptions , but apply it in a general sense. The segmentation is not to be based on the seal as the segment and has to be map based. Also, do you have intersections as a separate asset? I would with roundabouts but not with the normal type.

    I was sliding towards the crossroad option, but I would be interested in what others have done or think is a good idea.

    Ashley Bishop
    Asset Management Coordinator
    Benalla Rural City Council

  • 2.  RE: Road Segmentation

    Posted 13 February 2019 20:31
    Hi Ashley,

    There are a couple of good resources to use as a guide for road segmentation, one being the latest Austroads data standard published last month and also the Austroads documents on Levels of componentisation, link for download here:

    These are free to download.

    Also it may be worth contacting Christoph Eicher at Southern Downs Regional Council. They have a very comprehensive manual for the business rules for segmentation of their roads.

    MattRyelandInfrastructure Data Services Pty


  • 3.  RE: Road Segmentation

    Posted 13 February 2019 22:09
    Hi Ashley,

    As a rule of thumb, we keep segments at around 1 km, or nearest construction standard, intersection, or specific feature, as this generally aligns with rehab works. If you intend to use segments as a basis for managing pavement rehabilitation works / reseals, I would avoid using bends as it is generally not good to start / finish works on a bend, as you will have a join and it is difficult to keep the same design radius on the corner.

    Geoff Paton
    Blayney Shire Council

  • 4.  RE: Road Segmentation

    Posted 14 February 2019 15:54
    Hi Ashley
    We have 2km rural roads segments based on a rough achievable work in a day.
    I used mapbasic scripts to split the roads into segments, create segment marker points and 10m chainage points.
    Town streets are also segmented in the direction of numbering, with the through road owning the intersection.
    This is purely for work location with billing to the whole street site.
    Depending on the AMS you are using as to how you then add the other road assets
    Regards Peter

  • 5.  RE: Road Segmentation

    Posted 14 February 2019 15:55
    My advice is to segment your road data (and for that matter any data) into the smallest segments. Typically this would be intersection to intersection, but it could be smaller if something special warrants it.  Then use attribution to join segments if needed for a particular application.  It is always easier to join small segments together via attribution than to break them apart for some unforeseen reason.

  • 6.  RE: Road Segmentation

    Posted 17 February 2019 21:18
    Hi Ashley

    The following rules were developed for a remote Local Government client with both Urban and rural roads.  They wanted a relatively simple solution to segmentation.

    I'll add that the purpose of segmenting your network is to divide the network into manageable sections of road that perform consistently and fit your business need.  Every segment requires data capture and data management.  If you have a sophisticated road system with high demand and risk and a large budget (e.g. an urban City or Highway system) you likely need a sophisticated and detailed segmentation and analysis.  However that same approach for a remote low volume rural network where you have limited resources could cripple your decision making to no benefit with too much data and analysis you can't afford when your works approach will always be to manage large scale projects.

    There is also an emerging trend towards dynamic segmentation which I won't try to explain here except to say you store your different data in "discrete layers" and then when you analyse the network you create the rules of segmentation and extract the data based on what you need for that particular analysis.

    The following draft rules were developed to suit the specific business needs of that Local Government, including consideration of the scale of works projects they undertake, the specific risks and the design/asset management resources

    Hope this is useful 

    Segments shall be a maximum of 2km length  broken as follows...

    Segment Break points at





    1.   At start and end of road


    Cul de sac head, road start and end

    See Austroads for definitions of start and end.

    2.    Divided carriageways


    Second carriageway defined as separate segment

    May not be appropriate for this LG

    3.    Intersection (see note i)


    T intersections

    Cross Intersections

    Small roundabouts (note ii)

    Typically broken at IP point

    See detail rules on definition of roundabout

    4.    Large Roundabouts (see note ii)


    "W Road/N Road" Roundabout

     Circulating carriageway defined as a segment

    5.    At bridges (see note iii)


    "GrandLittleRiver Bridge"

    At centre of bridge

    6.    At start and end of fords and flood ways


    "Washout River" crossing

    Suggest fords and floodways be treated as separate segments because they are significant lengths and they have a distinctly different construction and performance

    7.    Where a pavement or surface changes significantly

    Change between unsealed, seal, asphalt, brick

    Should include boundaries between sections sealed at different times

    8.    At significant changes in road structure

    Change in width

    Change from un-kerbed/kerbed

    Where underground drainage is provided

    Where pavement changes

    This needs some work to accurately define what is a significant change in Port Hedland (note

    9.    At jurisdiction boundaries

    Connecting to a MRWA Highway

    Local Government Boundary

    Interface to a private road 


    10.  At town site boundaries

    Town site boundary

    May not be applicable here

    11.  At boundaries with private land and intersections with major private roads

    Join to the Port network

    Intersection with mine site road


    12.  At significant land marks


    Past the "Farmer Joe's entry"

    Rural areas only.  If there is a significant land mark

    13.  Where road classification changes (At significant changes in use or character of the road)

    Significant change in AADT, start/end of heavy vehicle route

    Use this criteria where there is a significant change in the character or use of the road that warrants different treatment.

    14.  At significant changes in performance of the road, terrain, geology, etc


    The section where "Pothole Road" crosses the dry lake and keeps getting potholes

    Use this where a significant section of road is performing significantly differently to the adjoining section

    15.  At boundaries of significant work or contract areas

    End of works completed in 2013/14


    Use this where a contract ended at a point between two other significant segment points



    (i)            Current strategy is to separate intersections as a separate segment.  This may be a functional need of software or a business decision.  This creates an extra level of complexity to limited benefit.  Intersections will usually be treated at the same time as the adjoining road

    (ii)           There are two schools of thought on roundabouts – treat them as just a traffic device or treat them as a separate segment of road.  Suggest generally treat small roundabouts as a "traffic device" because these will be treated at the same time and in the same way as the adjoining section of road.  The Towns larger highway roundabouts warrant creation as a separate segment as they will be managed and perform differently

    (iii)          Bridges are a separate and distinct asset.  Some LG's prefer to treat the pavement on the bridge as a separate segment but this has limited value and adds an extra data element to manage.  Fords and floodways are different because they always require escalated attention

    Graham Lantzke
    Principal Asset Engineer
    WSP Pty Ltd


  • 7.  RE: Road Segmentation

    Posted 21 February 2019 19:33
    ​​Thanks Graham, this is just about what I was looking for. I was already following most of the ideas. Bridges was the one I had the most trouble with. For a short bridge (Single span) just the continuation of the road but what about a multi-span bridge which may have a concrete deck?
    I was also thing of using the bridge as the segment start/end point regardless of the distance.
    Using only crossroads and bespoke end points seems to work, there is always one or two (ten or twenty) that don't want to follow the rules but generally speaking, but of course when you get out of the metropolitan area it all changes. I have confirmed what I was told about the 1 mile grids where many country roads cross each other at the 1.6km mark. (close enough to 2km).

    I had a look at the reverences other people have mentions (thank you to those as well).  No fixed rule seems to apply to all situations.

    I have printed it out and stuck it on the notice board. Full credit to you.

    Thanks again.

    Ashley Bishop
    Asset Management Coordinator
    Benalla Rural City Council


  • 8.  RE: Road Segmentation

    Posted 25 February 2019 21:19
    rounding up, 5cents worth
    In relation to points 7 & 8, they seem to suggest that there is a segment break at any change of pavement.
    I don't agree that this should create a segment break.

    If you use 2 km segments then each pavement change, regardless of type, within the segment is a asset within the parent, being the segment.
    As you do work, some Pavement assets will be combined, others may be created but the segment will always remain the holder of the pavement assets.
    This will also depend on whether your software is a flat DB or relational DB

    whether you agree or disagree, I found this easier to manage as the segment ID remains the same, only its parts change attributes.

  • 9.  RE: Road Segmentation

    Posted 04 March 2019 16:07
    Hi Graham,

    great documentation of segmentation rules. Do you also use traffic data? Also do you use GIS software for the segmentation or is it part of your asset management information system?


    Birgit Kruse
    Professional Spatial Data Analyst
    State Roads TAS
    Department of State Growth



  • 10.  RE: Road Segmentation

    Posted 04 March 2019 16:07
      |   view attached
    Hi Ashley,

    I've developed attached segmentation rules for my previous workplace.  Hope this helps. If you have any questions please feel free to ask.

    Kind regards,

    Lalinda Karunaratne
    City of Gosnells
    Senior Asset Management Engineer