Longest, Straightest Highways

[CNGL-Leudimin]

I've been to the three longest straights in my region this year. However I haven't done all of one of them (but I have done it previously). None of them are as long as those posted here, the longest one being only 11 miles long.

Similar distance to I-80 in Utah...  43 miles from Nuevo Laredo to the libre/cuota split Carr. Fed. 85.

I measured it to be 1.5 miles longer, to a roundabout in Nuevo Laredo.

I-80 in Nebraska between Lincoln and Grand Island.  That's about a 60-mile long straightaway.  Ugh.

Almost but not quite straight.  https://goo.gl/maps/vRyQxZBqpyA2

Chris claimed to have found a 75 mile straight there, but I debunked that.

[DeaconG]

US 19 & 27 in Taylor County, FL. 
US 1 in St. John's and Duval County from St. Augustine to the area around the Avenues Mall is 25 miles with only one curve.
FL 710 from Riveria Beach, FL to Okeechobee, FL is 50 miles straight hence the name Beeline Highway.
Alligator Alley is a mention as its pretty much straight.
US 27 south of South Bay in Florida.
FL 80 & US 98 for several miles in Palm Beach County even with 23 mile bend.

You forgot the Beachline between OIA and the SR 407 split in Brevard County? Bad Roadman65, bad! No donut! 

[Flint1979]

At 123 miles, North Dakota 46 is the longest straight road I can find in the United States.

[bugo]

At 123 miles, North Dakota 46 is the longest straight road I can find in the United States.

More like 42 miles.

[kphoger]

At 123 miles, North Dakota 46 is the longest straight road I can find in the United States.

More like 42 miles.

Yep.  The longest section without curves is just under 43 miles long.  The Wikipedia article is lying, and the article it cites as its source even says:

Every "straight" road shifts a little bit here and there, bending just a bit around a rock or a tree or making an adjustment to cross a bridge. So does Hwy 46.

Not to mention the fact that ND-46 is only 121 miles long, so 123 miles of it being without curves is a tad impossible.

[J N Winkler]

I-80 in Nebraska between Lincoln and Grand Island.  That's about a 60-mile long straightaway.  Ugh.

Almost but not quite straight.  https://goo.gl/maps/vRyQxZBqpyA2

Chris claimed to have found a 75 mile straight there, but I debunked that.

I-80 through Nebraska is a notoriously monotonous drive, but on casual inspection the longest uninterrupted length of apparent tangent alignment I see is between (roughly) milepost 322 and milepost 334, a distance of about 12 miles.

Between the I-76 split (Exit 102) and Grand Island (Exit 314), I-80 is actually a river-follower, though the stream in question is the Platte River, with a wide and shallow alluvial floodplain.  West of there, the longest length of apparent true tangent alignment runs west about 12 miles from a point just east of the Lodgepole exit (Exit 76).

Between Grand Island and Lincoln, a high percentage of I-80 is on tangent alignment and the roadway centerline hardly varies from being a half mile north of the section line to the south (typical alignment along the back edges of adjacent quarter-sections, to minimize right-of-way acquisition costs by eliminating the need to condemn large swathes of land for the access rights; I-70 in Kansas is similar).  However, the individual lengths of tangent are short because they are divided by lengths of very high-radius curve, each curve radius being probably on the order of 100,000 feet.

I-80 is actually fairly curvy from just west of Lincoln east clear to the Missouri River.

Bottom line:  the longest tangents I-80 can claim in Nebraska are 12 miles in length at most, which is precisely what one would expect from good alignment design for a rural freeway in level to rolling terrain.  However, it was built perhaps a bit too early to fully exploit advanced thinking in alignment design, which calls for tangent length to decrease across the board (ideally to the extent that there are no tangents at all) and for the line of the road, when viewed from the driver's perspective, to flow smoothly to the horizon in a way that discourages highway hypnosis.

[csw]

This section isn't perfectly straight, obviously, but I'd say the most "straight" in terms of monotonous driving that I've driven is US 24 from Peoria, IL, to Kentland, IN. Approximately 120 miles of two-lane driving with few hills and lots of corn fields.

[7/8]

I know the Seney stretch of M-28 is Michigan's longest straight highway, it's about 25 miles but seems longer. I think it's one of the longest straight stretches east of the Mississippi.

My brother (I was in the passenger seat) drove this today and it certainly is a long stretch of straight highway! I noticed a few stretches where a river/creek seemed to be surprisingly straight beside the highway on the north side. I don't see that on Google Maps though...

Anyway, here are two photos I took:

[ftballfan]

Some other long straight stretches in Michigan:
US-31 from north of Scottville to Hoague Rd near Free Soil (used to be longer when US-31 went into Scottville)
M-55 from Lake City to Houghton Lake
M-57 and M-46 are pretty much ruler straight through Gratiot County

[Flint1979]

Some other long straight stretches in Michigan:
US-31 from north of Scottville to Hoague Rd near Free Soil (used to be longer when US-31 went into Scottville)
M-55 from Lake City to Houghton Lake
M-57 and M-46 are pretty much ruler straight through Gratiot County

M-46 really has very few curves. From the eastern terminus to Washburn Road a stretch of 46 miles I can't find where it curves once. It curves in Saginaw a couple times but recaptures it's allignment on both sides of the Saginaw River going east and west out of Saginaw. Then other than the few curves between Vestaburg and Edmore it doesn't curve again until the M-66 multiplex. Looking at M-46 I'm confused on why the Seney Stretch would be considered the longest stretch of straight highway in the state.

[J N Winkler]

M-46 really has very few curves. From the eastern terminus to Washburn Road a stretch of 46 miles I can't find where it curves once.

I can.  There is a fairly high-radius curve between Byington Rd. and Lee Hill Rd. that is visible in StreetView.  There also appears to be another of higher radius around Hurds Corner Rd.  Even the straight stretch just west of US 127 has a slight curve around Luce Rd.

Looking at M-46 I'm confused on why the Seney Stretch would be considered the longest stretch of straight highway in the state.

The problem with Google Maps, which I assume is what you are using to check straightness, is that it is better suited for exclusion, not confirmation.  It requires going to the original construction plans to confirm surveyors' intent to lay out the roadway baseline as a perfect tangent.  It is typically engineers within the state DOT and perhaps some long-established contractors that have ready access to old construction plans, so these alignment feature maximum/minimum claims often start as scuttlebutt conversation among agency old-timers that seeps into the hobby.  "I remember . . .," they say as they sit around the campfire or whatever, and of course they never pull out the plans so one can actually confirm it in black and white.

This said, if "Seney Stretch" means the length of M-28 between Shingleton and Seney, I suspect it is considered "longest straight" because it is all true tangent alignment, with no curvature of the kind that can be found with careful manipulation of Google Maps zoom level on the parts of M-46 that appear straight on casual inspection.  Confirmation would, of course, depend on access to the original M-28 construction plans.  (I really wish Michigan DOT would put its as-builts on open public access; obtaining construction plans free through FOI can be done but is a cross between roulette and keyhole surgery.)

[csw]

SR 4 in Ohio is pretty much straight on from Sandusky to Chatfield, approximately 37 miles.

[kphoger]

SR 4 in Ohio is pretty much straight on from Sandusky to Chatfield, approximately 37 miles.

I'm going with 29 miles on this one, from Sandusky to Caroline.  It curves slightly at Caroline.

[Inyomono395]

CA 167 has about a 12 mile straight section, also has the lowest AADT in California.

[Hurricane Rex]

Oregon I 84 has a pretty strait section from mp 165 to mp 194, the second longest in Oregon.

One of Washington's longest: I 90 mp 151 to 175.

[mgk920]

I-41/94 in Racine and Kenosha counties - 24 miles

Although built on a section line, the actual I-41/94 roadway curves around quite a bit within its ROW.

One of the longest true 'tangents' in Wisconsin is WI 173 from just north of WI 21 (Valley Junction) to WI 80 (Babcock) - built on an abandoned railroad ROW, it is about 22 m/35.5 km dead straight and level.

I-39 is also dead straight between WI 73 (interchange 136) at Plainfield and just south of US 10 (interchange 158) in Stevens Point.

How long are the longest true tangents on WI 29 west of Wausau and on WI 57 between I-43 just north of Saukville and WI 32 near Elkhart Lake?

Mike

[paulthemapguy]

This isn't going to be any kind of record holder, but I've always been amazed by how straight US136 is in central Illinois.  From Rantoul west to central Mason County, it doesn't have any significant curves whatsoever.  This is a distance of about 84 miles.