There are a number of delineation and other treatments that can be applied or installed in the centre of the road including:
The determination of the type of feature to use in the centre of the road will be as a result of function, traffic volume and crash risk. On rural roads, the high-risk rural roads guide shows that the risk of deaths and serious injuries from head on crashes typically exceeds the run-off road risk at flows above 6,000 vehicles per day (vpd).
High-risk rural roads guide, 2011
This has resulted in a new emphasis on the importance of treatments in the centre of the road. There is a hierarchy of treatments providing increasing safety but at increased cost. Table 2‑4 shows the relationship between the level of safety of treatment, treatment philosophy and risk (derived using the high-risk rural roads guide), ONRC and indicative AADT.
For information on how raised medians are delineated refer primarily to:
Table 2‑4: Relationship between treatment in the centre of rural roads, treatment philosophy, ONRC and AADT
| Level of protection |
Median treatment |
Treatment philosophy |
Road classification (ONRC) |
Indicative AADT |
|---|---|---|---|---|
|
More safe
Less safe |
Median barrier |
Safe System transformation works |
Regional, national |
> 8,000vpd |
|
Wide centre-line treatment with ATP (possibly with flexible posts) |
Safer corridors |
Regional, national |
5,000 – 15,000vpd |
|
|
ATP on (or next to) centre-lines |
Safety management |
Regional |
5,000 – 8,000vpd |
|
|
Flush median |
Safety management |
Arterial, primary collector |
>5,000vpd and where there are frequent turning movements |
|
|
Marked centre-lines (includes standard white, yellow or combination of both types of markings) |
Safety management |
Arterial, primary collector, secondary collector, access |
<5,000vpd |
|
|
No marking |
Safety maintenance |
Access/low-volume road |
<200vpd |
