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08 Aug 09

What Can We Learn from the Dutch Self Explaining Roads?

Fascinating read about how the concept of "forgiving highways" (forged in the 1960s), and why it needs rethinking in built-up areas, and how the Dutch are leading the way.
QUOTE
Forgiving Highways is a concept that designs roads to “forgive” mistakes made on the road. It seeks to smoothly redirect the vehicles that leave roads, and allow wide enough clear zones to bring vehicles to controlled stops if and when they leave the roads. Breakaway supports, burying the end of guardrail, clearing the roadside of unneeded obstacles, and flattening and rounding slopes and ditch sections became standard design as part of the concept.

The idea that Forgiving Highways (wider and straighter) would reduce crashes on non-freeways took root during the 1966 National Highway Safety hearings.
UNQUOTE
Obviously, "forgiving highways" works well in a non-urban context, but in an urban context, arterials built with those guidelines provide a false sense of security for drivers, and leave pedestrians and cyclists (anyone "weaker") in the lurch.

I'm particularly interested in this entry right now, because it seems to me that the City of Victoria's Engineering Department is stuck in a "forgiving highway" mindset as it tries to convince us that the city's Johnson Street Bridge needs to be replaced.

blog.pps.org/he-dutch-self-explaining-roads - Preview

project_for_public_spaces roads transportation holland traffic traffic_safety

28 Apr 08

City road networks grow like biological systems - tech - 23 April 2008 - New Scientist Tech

- this is fascinating: road systems evolve more along "biological" lines, vs. according to master-planned dictates...

technology.newscientist.com/...w-like-biological-systems.html - Preview

infrastructure highway_system roads

French and US physicists have shown that the road networks in cities evolve driven by a simple universal mechanism despite significant cultural and historical differences. The resulting patterns are much like the veins of a leaf.
They found that cities' road patterns have a lot in common mathematically, as well as looking similar to the eye.
4 more annotations...
- The main influence on the simulated network as it grows is the need to efficiently connect new areas to the existing road network – a process they call "local optimisation". They say the road patterns in cities evolve thanks to similar local efforts, as people try to connect houses, businesses and other infrastructures to existing roads.
  
  Evolution has ensured that local efficiency also drives the growth of transport networks in biology – for example, in plant leaf veins and circulatory systems.
  
  "Cities are not just the result of rational planning – in the same way that living organisms are not simply what is in their genetic code," Barthélemy told New Scientist.
- The study's results might be important for understanding urban growth and "sprawl" says Barthélemy. More than half the world's population lives in cities, a proportion that continues to increase.
  
  "The approach could even help city planners to better predict how some street networks will evolve and to plan accordingly," he adds.
- Previous models of urban development assumed that efficient transport across the entire network motivated the system's growth – as if planned from the top down. Focussing instead on the structure of local connections seems truer to real life, says Flammini.
  - Yes. - on 2008-04-28
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- Using the local efficiency of connections to drive road network growth looks to be a truer fit with reality than using the total cost of travelling across the network, says Onnela. "Especially given that the time scale of city growth (possibly thousands of years) and the time scale of urban planning (perhaps tens of years) are so clearly different."

23 Oct 07

THE GENIE IN THE BOTTLE: The Interstate System and Urban Problems, 1939-1957

www.tfhrc.gov/...urban.htm - Preview

automobile blight infrastructure planning reference roads transportation

"The plight of the cities,"
the report states, "is due to the most rapid urbanization ever known, without
sufficient plan or control." The focal point of all cities, the central business
district, was "cramped, crowded, and depreciated."