Regional Boards > Mid-South
US-290 between Austin and Houston thread (future freeway-ish upgrades when?)
Bobby5280:
What about all the numerous Interstates that don't have a median? A bunch of them have only a concrete Jersey barrier or even a mere cable barrier separating the two directions of traffic. New segments of super highways signed as Interstates get built like that all the time.
The main difference I see with modern Interstate standards is better/longer ramp designs and wider shoulders. I'm sure there are other things involving how smooth the road should be (not a bunch of rolling dips and rises). Median width doesn't seem to be a big issue. Not unless the median will have no physical barriers, be it concrete or cable barriers.
J N Winkler:
--- Quote from: kphoger on March 21, 2023, 02:39:32 PM ---
--- Quote from: ethanhopkin14 on March 21, 2023, 02:10:20 PM ---I wasn't talking about the shoulders. There are more to the standards than the shoulders. The median feels too narrow here. I am not talking about getting out and throwing a tape measure on it.
--- End quote ---
Interstate standards call for a median of at least 50 feet. It might be a couple of feet short of that standard.
--- End quote ---
I threw the tape measure or, rather, the Google Maps measure tool. What you say is correct on both counts--minimum median width in rural areas is 50 feet and I-69E/US 77 appears to have a median width of 48 feet at this location. However, it does have cable barrier.
The 2016 edition of the Interstate standards uses the word should for median width, but shall for other criteria such as shoulders and unit lane width, which suggests to me that there is more leeway for medians.
--- Quote from: Bobby5280 on March 21, 2023, 07:05:35 PM ---What about all the numerous Interstates that don't have a median? A bunch of them have only a concrete Jersey barrier or even a mere cable barrier separating the two directions of traffic. New segments of super highways signed as Interstates get built like that all the time.
--- End quote ---
A barrier of some kind (cable or Jersey) is the usual get-out. The 50-foot minimum applies just to flat and rolling topographies in any case.
Another aspect of median design referenced in the Interstate standards is that the median should not be engineered to drain over the traveled way. However, first-generation public-authority turnpikes (including the rural lengths of I-44 in Oklahoma) still hang on to Interstate status despite not honoring this guideline.
sprjus4:
--- Quote from: J N Winkler on March 21, 2023, 11:37:44 PM ---The 2016 edition of the Interstate standards uses the word should for median width, but shall for other criteria such as shoulders and unit lane width, which suggests to me that there is more leeway for medians.
--- End quote ---
There definitely is. Texas seems to either use 48 foot for standard median width on new construction (some exceptions do exist with wider), or a concrete barrier only (narrow median).
North Carolina uses 46 foot median for the most part, including over 100 miles of I-40 built between Raleigh and Wilmington in the 1980s. Even the newer addition freeways have areas with 46 foot median. There’s nothing wrong with it.
I wouldn’t advise narrow medians on new construction, but incorporating an older freeway segment with a narrow median (after installing cable barrier at the minimum) that meets interstate standards otherwise (full access control, full paved shoulders, etc.) should be, and is allowed.
Kentucky’s segments of I-69 along the existing parkways have a 35 foot median I believe, and they’ve all been incorporated. There wasn’t even a cable barrier installed in most places. I believe from a safety standpoint, those should be incorporated regardless of standards or not. You have two dual roadways with opposing 70+ mph traffic that close, there ought to be a barrier.
kphoger:
--- Quote from: J N Winkler on March 21, 2023, 11:37:44 PM ---A barrier of some kind (cable or Jersey) is the usual get-out. The 50-foot minimum applies just to flat and rolling topographies in any case.
--- End quote ---
To wit, medians in urban or mountainous areas (which is where barriers are mentioned) are required to be "wide enough to accommodate the left shoulder width plus the space needed for a barrier". This seems to assume that barriers are only ever used in urban or mountainous areas, but such is obviously not the case.
thisdj78:
TXDOT is taking public comment on its 2050 plan until May 31st. Being that I do not see any plans for US290 or SH71, I will be submitting a comment on the need to expand these corridors:
Email: ConnectingTexas2050@txdot.gov
http://txdot.gov/en/home/projects/hearings-meetings/transportation-planning/connecting-texas-2050.html
*If the above link doesn’t work, try getting there from this article:
https://communityimpact.com/austin/central-austin/transportation/2023/03/23/heres-how-you-can-provide-input-on-the-statewide-transportation-plan-for-2050/
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