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Author Topic: CA-58 Kramer Junction Bypass  (Read 42044 times)

sprjus4

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Re: CA-58 Kramer Junction Bypass
« Reply #300 on: May 23, 2020, 03:40:06 PM »

80 mph would be appropriate and in line with other western states on rural freeways.

I don't think any of the three west coast states has any posted speed limits over 70 mph.
Washington allows 75, and I heard that they were going to post it on I-90, but I don't think they have yet.

WSDOT did a study and determined that the projected time savings didn't outweigh the projected increase in crashes, so it won't be happening.

I think all of you assuming the engineers would be raising limits extra high everywhere are a bit optimistic. From my couple years' experience in the field, engineers are definitely more on the cautious side when it comes to design standards, and all you have to do to see that is look at the speeds posted on warning signs for curves and intersections and such. In fact, those are purposely posted 5-10 mph under the design speed of the curve to allow for a safety margin, and the MUTCD even says this explicitly in its standards for them.

And if you think about putting yourself in the position of the engineer, you might be hesitant to set a speed limit right at the design speed because there is no room for error, leaving you potentially liable if you cannot justify that decision in a lawsuit after multiple crashes happen on the highway you designed.

In any case, unless California decides to start strictly enforcing their speed limits, I don't see them as a problem at all. Most traffic flows at near 80 mph in 65 zones, even in urban areas. In fact, I drove across the whole state north to south and back last September and had no issues going 78-80 in 65 zones and 83-85 in 70 zones the whole way, for 1600+ miles. In fact I only remember seeing maybe 2 officers checking speeds, and they were pulling over the traffic that was surely going as fast as I was.
It's already been proven multiple times that increasing the speed limit by +5 only increases 85th percentile speeds by 2 or 3 mph at most. Most people drive at a speed they're conformable with, and the closer the speed limit is to that, the less speeding occurs.

I don't buy this whole "safety" nonsense. People aren't going to be going 85 - 90 mph now that it's 75 mph. From my experience driving in Texas, people in the 75 mph zones drove usually at or under 80 mph, with some going up to 85 mph. In the 80 mph zones, people usually drove at or under 85 mph, with only a few going above 85 mph. In the one 85 mph stretch near Austin, nearly everybody drives 90 mph or under, very rare to see anybody surpass that, and if they do, it's still under 95 mph. Some people like to push it to 100 mph since the limit gets close, but that's not the majority of drivers. For me, I have no problem driving 75 - 80 mph in a 75 mph zone, 80 - 82 mph in an 80 mph zone, 85 - 87 mph in an 85 mph zone, though in a 70 or 65 mph zone I may drive 75 - 80 mph, especially on rural segments.

On two lane roads with 70 or 75 mph in Texas, it's rare to see people exceed the limit, especially by +5 mph. Again, if the speed limit reflects the design of the road, people will have no problem obeying it. Post it low, and there's speeders. Then there's people who believe if you raise it, everybody will speed by 5-10 mph which is simply not true.

75 mph would be an appropriate speed limit for I-90 in Washington, and I find it hard to believe crashes would significantly increase. I'm willing to bet most people already drive 75 mph to 80 mph, and increasing it would not change that figure more than maybe 2 or 3 mph. It would bring the speed limit closer to reality, and the number of people disobeying it would be lowered.
« Last Edit: May 23, 2020, 03:46:03 PM by sprjus4 »
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stevashe

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Re: CA-58 Kramer Junction Bypass
« Reply #301 on: May 24, 2020, 02:08:33 AM »

75 mph would be an appropriate speed limit for I-90 in Washington, and I find it hard to believe crashes would significantly increase. I'm willing to bet most people already drive 75 mph to 80 mph, and increasing it would not change that figure more than maybe 2 or 3 mph. It would bring the speed limit closer to reality, and the number of people disobeying it would be lowered.

Funnily enough WSDOT effectively used that fact (that speeds only increase by 2-3 mph) as a reason against raising the speed limit since assuming there will only be a couple minutes' worth of time savings causes the cost/benefit calculation to rule in favor of preventing even a very small number of extra crashes over saving barely any time. And I don't think they considered "number of people disobeying speed limits will decrease" at all or maybe the outcome would have been different. Link to a summary of the study is below.

https://www.wsdot.wa.gov/planning/Studies/i90speedlimit/default.htm

Personally I do think 75 would be appropriate on the section of I-90 they were considering since it has the least amount of traffic, is very straight and flat, and almost exclusively serves long-distance traffic between Seattle and Spokane.

I'd also be in favor of posting the freeway sections of 58 at 70 mph. I do have reservations about posting any road with cross traffic at 70. Sure there are states like Montana and Texas that do have limits that high or higher but I'm sure the traffic volumes there in most cases are significantly lower. In a similar vain, I'd also argue 75+ is too fast for the vast majority of freeways in California since even the rural sections have much more traffic than other states that use higher limits. Exceptions to this may be I-40, eastern portions of I-8, and maybe I-10.
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sprjus4

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Re: CA-58 Kramer Junction Bypass
« Reply #302 on: May 24, 2020, 02:22:16 AM »

Sure there are states like Montana and Texas that do have limits that high or higher but I'm sure the traffic volumes there in most cases are significantly lower.
Not necessarily... in Texas at least there's numerous examples of divided highway segments with at-grade intersections carrying 15,000 - 30,000 AADT and are posted at 75 mph, including some corridors with high truck percentages such as US-59, US-77, US-281, US-84, and others.

From my experience driving on CA-58 before, I'd say 70 mph would be appropriate. Most traffic already does 75 - 80 mph, so it's not like it would make much of a difference. Most of the at-grade intersections that are spread far apart are minor.

In a similar vain, I'd also argue 75+ is too fast for the vast majority of freeways in California since even the rural sections have much more traffic than other states that use higher limits. Exceptions to this may be I-40, eastern portions of I-8, and maybe I-10.
SH-130 near Austin is posted at 80 mph with over 60,000 AADT.

75 mph is posted on many interstates carrying over 30,000 AADT, including I-35 between Austin and Dallas-Fort Worth seeing over 50,000 AADT.

Funnily enough WSDOT effectively used that fact (that speeds only increase by 2-3 mph) as a reason against raising the speed limit since assuming there will only be a couple minutes' worth of time savings causes the cost/benefit calculation to rule in favor of preventing even a very small number of extra crashes over saving barely any time. And I don't think they considered "number of people disobeying speed limits will decrease" at all or maybe the outcome would have been different. Link to a summary of the study is below.

https://www.wsdot.wa.gov/planning/Studies/i90speedlimit/default.htm
Interesting they use "average speed". If "half the drivers" are traveling at 73 mph, that means there's much faster speeds on the higher end. What's the 85th percentile? I'd estimate closer to 80 mph. There's no reason I-90 shouldn't be raised to 75 mph.
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