In this recent post Matt asked why we were still building dangerous intersections. One part of his post caught my eye, specifically proposed changes to the intersection of SH1 and SH26 in the Waikato. The location of this intersection is shown below.
You can see that the intersection exists firmly within the Hamilton urban area. Moreover, I understand the area to the east is planned for residential growth in the future. I.e. there will be more and more residential development to the east.
The reason this caught my eye is because the proposed changes, in my opinion, seem likely to result in a horrific clusterfuck of an intersection that will, at a minimum, destroy urban amenity and, potentially, result in pedestrian carnage. In my opinion, this roundabout design is completely inappropriate for an urban area. And unlike NZTA I don’t agree t hat potential delays to vehicles are sufficient reason to provide wholly unsatisfactory facilities for pedestrians. Facilities that are so lacking that they seem likely to increase the risk of injuries to pedestrians who need to cross at this intersection.
The proposed changes are illustrated below.
Now I should mention that the NZTA press release for the changes mentions an additional pedestrian crossing is to be located on SH26 to the east, which I presume (although can’t be sure) is beyond the extent of works shown above. The press release also noted the presence of a pedestrian underpass on SH1 to the south, which is being retained in the new design.
What NZTA are proposing for the southern and eastern approaches to the roundabout is relatively poor practice and ill-suited to an urban area such as this.
But perhaps most importantly, the proposed pedestrian facilities don’t seem to address what happens on the western approach to the roundabout. As anyone can easily see from StreetView below, NZTA’s beautiful junkspace landscaping is *already* being severely trampled beneath the feet of hapless pedestrians as they scamper across the existing road. QED there’s an existing problem that needs to be resolved, not ignored as the proposed design has done.
Anyway, I was sufficiently motivated by this proposal to start digging for more information.
The background study for these intersection changes was completed in 2008. Given that it’s now almost 8 years since the study was completed, I thought I’d go and look at traffic volumes since that time. In the figure below I’ve totalled the AADT on the two closest counts on SH1 and SH26 over time (NB: This will double-count many vehicles, which is why the total AADT shown here is significantly higher than the figure of 37,000 vehicles per day using the intersection that is quoted in the NZTA in their press release. Nonetheless it’s likely to be broadly indicative of general trends in AADT).
The volumes bobble around a bit, although current AADT is about 3% below the level achieved in 2008, i.e. the time that the report supporting the proposed changes was developed. Is it reasonable to assume that vehicle volumes will increase or decrease from here?
Well, there’s some growth out this way so it’s plausible to suggest there may be more demand. On the other hand, there’s one major question that I’m not confident is addressed by the studies associated with this upgrade: The Waikato Expressway, specifically the Hamilton section.
For those who aren’t familiar with this project, it’s part of the RoNS programme.
While I’m no fan of the RoNS programme per se, if these projects are to go ahead then I would at least expect NZTA to maximise their potential benefits, especially with regards to re-configuring parallel routes to support more livable urban places. In this context, the Hamilton section of the Waikato Expressway is high-speed, high-capacity route that seems likely to shift vehicles away from the existing SH1 and away from this roundabout. Construction of the Hamilton section is expected to start in 2016 with a target opening date of 2019.
I note that the NZTA website states that the Hamilton section of the expressway will:
- Connect the Ngaruawahia section of the Expressway, completed in late 2013, to the Cambridge section, due for completion in late 2016.
- Reduce traffic congestion and improve safety on Hamilton’s local road network by significantly reducing through traffic.”
And yet NZTA’s proposed changes to the SH1 and SH26 intersection (which appear to have been formulated prior to the RoN being confirmed) are designed to increase capacity.
One has to wonder why the NZ Transport Agency is spending $2 million to create a situation that is more dangerous for pedestrians than the present one, while at the same time spending the best part of half a billion dollars building a high-speed bypass around the same intersection.
Call me a simpleton if you will but I would have thought the more logical sequence of actions would be:
- Complete the Hamilton section of the Waikato Expressway in the next 3 years as planned; and
- Monitor changes to vehicle volumes in response to growth (which apparently is quite low at the moment) and expressway; and
- Develop options for the intersection which respond to these changes, but which are also appropriate for an urban area.
In terms of #3, this really brings us full circle. I cannot understand why NZTA would think the proposed design is appropriate for an urban area. I can tell you that in my opinion it’s most certainly not. While I’ll reserve my full and final judgment until I have more detailed information to consider, the proposed intersection seems to compromise pedestrian safety to a level bordering on negligence.
I know that’s a big call so let me present some reasons why:
- The design does not seem to meet the present need for a pedestrian crossing on the westbound SH1 approach, e.g. to access the adjacent school. There is already demand for this pedestrian movement, as we can see from StreetView. This demand will only increase as the area develops in the future.
- The approaches are wider than the current facility. The western approach on SH1 , for example, is three lanes wide. This will increase the distance pedestrians will have to cross before they reach the landscaped sliver of land in the middle of the road.
- The design incorporates features that seem likely to increase vehicle speeds. The western approach on SH1, for example, now includes what is effectively a “slip lane” for vehicles travelling through. This features will enable/encourage vehicles to maintain their speed on their approach to (and exit from) the intersection. This will increase risks to pedestrians who (legitimately) need to cross the western approach, and the severity of accidents.
I draw two *preliminary* conclusions from all this. First, the proposed changes to the intersection is unacceptably dangerous for pedestrians and should not proceed as designed. Second, the proposed intersection has been designed without consideration of the Waikato Expressway and thus are likely to represent poor value for money and low strategic fit.
I’d really like to know what others think: Am I mis-reading the situation here? Or is it as bad as it looks? An outdated and seemingly dangerous design being imposed on what is very much an urban area, just prior to a major expressway bypass opens? What is going on?