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Car flying over a roundabout literally

Started by roadman65, February 19, 2020, 12:02:10 PM

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sparker

#25
^^^^^^^^^^^
The fact that jakeroot recognizes that roundabouts have functionally become default installations in some jurisdictions is in itself promising -- but knowing that fact may not lead to recognition of that phenomenon as a potential problem.  When it comes to such things, each situation -- ideally when it comes to the safety of the driving public -- needs to be assessed as a unique set of circumstances with singular characteristics.  Default designs and the deployment of such on the whims of agency planners do no favors to the public.   And recognition of the difference between appropriate design for rural vs. urban situations should be "Reality 101" within both the academic and administrative realms.  "One size fits all" is simply an exercise in intellectual laziness (pardon me, but that's one of my lifelong pet peeves!). 

I'll venture an opinion here -- anyone looking to enter public service within any agency engaged in planning or regulation owes it to themselves and the public they purport to serve by obtaining and reading John Kingdon's seminal 1984 tome Agendas, Alternatives, and Public Policies; try to get the '95 2nd edition, although the original remains worthwhile.  Throws a lot of light regarding how policies are initiated and then evolve in the legislative and administrative arenas. 


DaBigE

Quote from: jakeroot on February 23, 2020, 10:05:43 PM
Quote from: sparker on February 23, 2020, 09:57:15 PM
^^^^^^^^^^^^
And I'll stand by my opinion that while roundabouts may be appropriate for lower-speed urban/suburban applications, deploying them along high-speed rural facilities is at best questionable and at worst dangerous.  CA 12/113 certainly needed improvement, but channelization and improvement of lines of sight would have been a more judicious approach rather than applying the seeming method du jour of Caltrans -- when in doubt, put in a roundabout (hey, that rhymes!).:D  Maybe they're just tired of maintaining the electronics required for a signalized installation.  In any case, it seems to be a case of the "garbage can" syndrome -- a favored solution looking for a place to be applied.

I feel like roundabouts and DDIs are both favored solutions looking for places to be applied, with the difference being that DDIs actually have a good crash record (from what I've heard at least ... would appreciate some hard data on the matter at some point). Roundabouts seem to be a favorite among several states (and/or jurisdictions within), particularly Wisconsin, Washington State, Florida, Colorado, Kansas, Maryland, and others. IIRC, Wisconsin even had (has?) a protocol that required roundabouts be the primary alternative design for upgraded intersections, with signals and four-way stops needing further reasoning/explanation to implement (DaBigE probably knows best).

Saying "primary alternative" is dangerous. As much as some would like to believe, roundabouts are not the default alternative to have to be otherwise disproven. Wisconsin's ICE policy is to consider (Read: evaluate) the feasibility of a roundabout whenever a traffic signal is proposed, among a list of other alternatives. The viability of any intersection control alternative is reviewed based on construction and maintenance costs, ROW acquisition, environmental impacts (wetlands), expected operations/LOS, oversized vehicle routing, and crash mitigation potential.

If a traffic signal is being considered, it typically means a TWSC or AWSC has failed, either operationally (volume) or due to safety issues. The typical progression is TWSC -> AWSC (which is supposed to be a temporary/interim solution per DOT policy -> traffic signal/roundabout/DDI/SPI -> grade separated intersection. I've been around the process long enough to not only have seen many roundabouts eliminated from consideration as part of this process, as I personally have completed a report recommending something other than a roundabout.

It's been a while since I've had to do one there, but IIRC, MnDOT has a similar procedure as well.
"We gotta find this road, it's like Bob's road!" - Rabbit, Twister

SSR_317

Judging from the tracks I saw in the snow on Thursday, it appears someone westbound on 96th Street at Hazel Dell Parkway in Carmel, IN tried to emulate this Cali driver very recently. No deviation from a straight line whatsoever, just up and over the roundabout's median.



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