Heavy Haulage

Traffic Management should prepare for oversize

By Jonathan Bhana-Thomson, chief executive, NZ Heavy Haulage Association.

We are already well into this construction season, but it is always time to think about the impact of works sites happening in the road corridor on those using the road for freight transport.

In particular the impact on the transport of oversize loads.

The NZ Heavy Haulage Association regularly hears from our member companies that transport large loads around the country, that often road works sites do not consider what would happen if a large load turns up at the site, and how this load would be able to transit through the work zone.

In addition we often deal with roading projects that have had their work and site disrupted by the unexpected arrival of an oversize load.

Practically all State Highways and most arterial routes in larger urban areas are used by oversize loads and while there are specific travel times to limit the travel of loads to times that do not include peak hour traffic, at other times it should be expected that oversize loads will be using these routes.

In and around many urban areas the largest oversize loads must abide by the rules to travel at night, when other traffic using these roads is at its lowest, however this is also the time when many of the most significant works on the road also happen – for the same reason.

On this basis then, those people putting together Traffic Management Plans need to factor in that oversize loads will be arriving at the site, and what contingencies will be included in their Plan for dealing with this situation efficiently.

One important note to remember is that often any detour routes are not suitable for oversize loads, due to infrastructure design, permit restrictions, low overhead wires and the like. It is therefore important to talk with industry about how suitable detour routes are.

While there are many different sizes of oversize load, for the purposes of a Traffic Management Plan, Plan designers should cater for two main types and sizes of load.

Heavy haulage transporter

The first main type of oversize load is a piece of heavy machinery on a low loader transporter. The transporter itself will be at least 3.1 metres wide on the pavement (and often wider) and this presents the first problem in that lane widths between cones will often be narrower than this at worksites.

While we understand that narrower lane widths do slow traffic down, it does mean that cones (and sometimes barriers) will need to be moved to allow oversize loads to travel through. While some pilots may be able to assist with this, remember that load pilots are there for the safety of other traffic and their primary attention will be on stopping/directing other traffic. Therefore depending on the location, traffic management staff may be called on to undertake this task.

Often the load will be much wider than this – out to more than 4m in width, and this needs to be taken into account when thinking about safe work areas and the positioning of work equipment. Trailer heights are often at 900mm off the pavement, around the same height as that of traffic cones and safe hit posts.

It depends on the work site configuration, but in most cases all on-coming traffic will need to be stopped, and the load brought through.

If the TMPs can contact the Association then we can put communications out to the industry where major works sites are located and also contact details for STMSs or project managers, so that transport operators can give prior notice about their load coming through.

In our view, all this information should be captured and provided for in a TMP, the same as pedestrians, cyclists and other special users of the road corridor are provided for.

Wide house on transporter

Oversize Houses and other loads can be regularly permitted for loads up to 11 metres in width, and for many roads around our country, this would take up the entire road width. For a good part of the country these loads have to be shifted at night, for other areas early evening and during the middle of the day are permitted for travel.

This means that depending on an individual worksite, that a contingency plan should be in place to allow these very wide loads through. Written into the TMP should be provisions that:

  • Contact information for the project to be made available to the industry via the NZ Heavy Haulage Association at least the week prior to work commencing;
  • On the basis of notified and planned loads, that these should be permitted access through the website, while other traffic is held at each end;
  • Traffic management staff should assist with the moving and replacement of any cones and signage required as part of the TMP;
  • That where the site is unattended (for example daytime work that is stopped overnight) that the location of machinery should be away from the road lanes, and that where speed signs are located in a gateway effect, that where possible that these are offset to remove the need to lay them down and replace them.

This will enable the oversize load to cause the least disruption to the worksite and for the safe and efficient movement of large loads on the roading network.

So the take home message is that this association does advocate that the provision for oversize loads through worksites are specifically detailed in a TMP, as this gives certainty for both parties about the way to proceed.

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