Category Archives: parking

Speed Design Vs Posted Speed

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The point of this post is to show a weak link between design speed and posted speed, and to illustrate that the optimum posted speed limit is set more by leaders than engineers.

A 5 km/h speed sign is what one sees when entering the car-park at Te Rapa PlaceMakers, while entering Bunnings car-park the speed is assumed to be 50 km/h. They are similar car-park designs, types of business and client types.

A 10 km/h speed limit is used at all supermarket car-parks unless you’re shopping at Countdown

15 km/h is the speed at Countdown supermarkets, unless you shop at Countdown Liverpool St, which is 10km/h. There are no engineering, design, franchise or user differences. What makes things different is the managers’ thinking about the level of risk and what is a ‘reasonably practicable’ speed to reduce the risk of harm.

20km/h is a benchmark speed. The AustRoads safety team, which led the Grey St safety improvement plan, mentions that speeds of around 20 km/h are used to avoid serious injury. A 20km/h limit is used in the German city of Koblenz for its city centre streets. The road use in central Koblenz isn’t different to Hamilton’s Barton St (30km/h) or Victoria St (50km/h between Bryce St and London St); only the risk of serious harm from speed is different.

30km/h is now what 50km/h was last century. Most urban areas in Europe use 30km/h as a default speed. There is a good reason: “for a speed choice of 30 km/h instead of 50 km/h, the estimated reduction in fatal crash risk is 95%” (from the AustRoads safety team that led the Grey St safety improvement plan). Even the Chief Executive of AA advocates for 30km/h speed limits. In Seattle, the speed limit on all residential (non-arterial) streets is 20 mph [30km/h], and the speed limit on arterials is 25 mph [40km/h], unless otherwise posted. Speed is the critical factor in the severity and frequency of crashes. Learn more about why Seattle lowered speed limits in 2016.

A 40km/h [25 mph] default speed is used increasingly across cities in the USA. Speed is the key to reducing the severity of harm resulting from mistakes. For Example: “Since 2014, [in] New York City … the city’s traffic fatalities have declined 28 percent with a 45 percent decline in pedestrian fatalities — bucking national fatality trends, which have increased 15 percent over the same period.”

50km/h is a misused speed in urban areas. It is seen to be an efficient speed for journeys that involve moving a very large number of motor vehicles along a single lane. The problem is that cities are made up of places, where people walk from homes or car-parks to socialise face-to-face, to shop, to go to school, or many other day-to-day activities, all of which involve crossing roads as pedestrians. A pedestrian will be almost always seriously harmed, and in fact has a 50% chance of being killed in a conflict with a person driving a car travelling at 50km/h. Never mind who makes the mistake, the pedestrian is always the victim.

Parking evidence

“If restraints on the parking supply really did limit economic vitality, one would expect to find some evidence, but there is none” Page 558 Christchurch – Central City Technical Appendices E-P01

If increased parking supply really did attract more pedestrians, one would expect to find some evidence, but there is none. (Page 35-ref.1)

It is then suggested that “increased commercial car park capacity indicates a shift from pedestrian to car-based access to and around the centre” (Page 35-ref.1.) One would expect to find some evidence, but there is none (the Vehicle Count is in the Hamilton central area only).

Maybe a 6-lane road (4 for car movement lanes plus 2 lanes for car parking) on a sunny day would make an attractive place. One would expect to see some evidence.

If free parking at competing retail locations stopped people going to places where they pay upfront for parking, one would expect to see some evidence. Here I’m suggesting the 2007/08 GFC reduced car use, which reduced CBD parking revenue.

Sorry, one more graph:  below we see the effect of changing retail locations. Note: only the CBD charges parking as a separate cost, so in 2005/06, Rototuna and the Base came alive but the CBD didn’t have a step change in sales until about 2010, as The Base was investing in more retail space.

To finish, here is a link to a report titled ‘Hamilton’s retail economic effects associated with the Base’ (Page34-Ref:2)

“13.33) [Paul P Keane] view is that a large proportion of the sales would have been lost to Hamilton. They would either not have been made at all – that is, households would simply spend less on retail – or they would have been made in other cities instead, such as Auckland, Tauranga or Rotorua, resulting in outwards leakage.

13.34) By creating The Base as a regional centre, Chartwell as a community (or sub-regional) centre, and Centre Place as the retail heart of the CBD, the opportunity for customers to do their shopping in Hamilton was far more likely than those sales going elsewhere, or not going anywhere.”

Ref: 1 – EPA Ruakura Economics Philip McDermott

Ref: 2 – Hamilton PODP Hearing Business Zones Mon4Nov2013 P Keane Evidence TGHL


Category: CBD, News, parking