Which state highways should have a speed study?

[mcdonaat]

Received this nice little email today from a DOTD Customer Service guy -

Mr. McDonald,

If you have a specific location we can have the traffic section study, but there are not speed studies for entire interstate or statewide routes. Speed limits are pre-determined by the FHWA for roads that have specific criteria, for example, number of lanes, dividers, access points, urban/suburban etc.

Anyone have a serious route they would like the traffic section to study? The only statewide route I entered was US 65 from LA 15 north to I-20, then Tallulah to the Arkansas state line. The rest are 4- or 5-mile routes that serve as a hazard for a low speed limit. If this all gets done and updated, we might be able to see 2-lane roads with 60 MPH signs, or even the Pineville Expressway with a 70MPH limit where it's an open highway.

Serious responses only!

[NE2]

I-366 will be 85 mph.

[Alps]

Speed limits are pre-determined by the FHWA? Bet they don't even know they have that kind of power.

[Alex]

The whole 1998 study about elevated Interstate highways mandated at 60 mph should be reviewed again.

Found this press release which explains the 60 mph stretch of I-310 among others:
http://www.dotd.louisiana.gov/pressreleases/Release.aspx?key=355

[mcdonaat]

Our traffic manager are regularly measuring and studying the traffic issues around the state. Sending us a list of roads we are already monitoring would not benefit the situation. If you have a specific issue at a specific location, we can certainly look into it, but as I pointed out in a previous email, many of the issues you raise are already addressed by federal standards that determine the speed for specific categories of roadway. If there is a specific problem that you would like to see addressed, i.e. crashes, speeding, unsafe conditions, please point that out and the location where the issue exists and we can study it. To randomly choose a length of highway to consider for a study without an issue would not be beneficial as there are plenty of other issues for our traffic mangers to address.

So the idea is that the "federal standards" are what's holding the state back... the guy doesn't want to admit that the DOTD has every right to set speed limits for themselves. LA 2 and TX 49 are a perfect example - LA 2 is a two-lane undivided highway with shoulders and a wide right of way. TX 49 is a two-lane undivided highway with shoulders and a wide right of way. The only difference is the state that the highways are in. LA 2 is 55 MPH, TX 49 is 70 MPH. My main push is for LA 2 to be 70 MPH to at LEAST LA 1, and a few of the US routes around the state should be bumped up to at least 60 MPH.

[Anthony_JK]

Our traffic manager are regularly measuring and studying the traffic issues around the state. Sending us a list of roads we are already monitoring would not benefit the situation. If you have a specific issue at a specific location, we can certainly look into it, but as I pointed out in a previous email, many of the issues you raise are already addressed by federal standards that determine the speed for specific categories of roadway. If there is a specific problem that you would like to see addressed, i.e. crashes, speeding, unsafe conditions, please point that out and the location where the issue exists and we can study it. To randomly choose a length of highway to consider for a study without an issue would not be beneficial as there are plenty of other issues for our traffic mangers to address.

So the idea is that the "federal standards" are what's holding the state back... the guy doesn't want to admit that the DOTD has every right to set speed limits for themselves. LA 2 and TX 49 are a perfect example - LA 2 is a two-lane undivided highway with shoulders and a wide right of way. TX 49 is a two-lane undivided highway with shoulders and a wide right of way. The only difference is the state that the highways are in. LA 2 is 55 MPH, TX 49 is 70 MPH. My main push is for LA 2 to be 70 MPH to at LEAST LA 1, and a few of the US routes around the state should be bumped up to at least 60 MPH.

Ahhhh...TX 49 is a Super 2 designed to be upgraded to a 4-lane tollway; LA 2 is a typical rural highway. NO WAY are they the same, and HELL TO THE NO, they should not be bumped up to anywhere above 55 or 60 mph.

Only fully controlled access highways (freeways and tollways) should be set at or above 60 mph...and only in rural areas.

[wtd67]

Our traffic manager are regularly measuring and studying the traffic issues around the state. Sending us a list of roads we are already monitoring would not benefit the situation. If you have a specific issue at a specific location, we can certainly look into it, but as I pointed out in a previous email, many of the issues you raise are already addressed by federal standards that determine the speed for specific categories of roadway. If there is a specific problem that you would like to see addressed, i.e. crashes, speeding, unsafe conditions, please point that out and the location where the issue exists and we can study it. To randomly choose a length of highway to consider for a study without an issue would not be beneficial as there are plenty of other issues for our traffic mangers to address.

So the idea is that the "federal standards" are what's holding the state back... the guy doesn't want to admit that the DOTD has every right to set speed limits for themselves. LA 2 and TX 49 are a perfect example - LA 2 is a two-lane undivided highway with shoulders and a wide right of way. TX 49 is a two-lane undivided highway with shoulders and a wide right of way. The only difference is the state that the highways are in. LA 2 is 55 MPH, TX 49 is 70 MPH. My main push is for LA 2 to be 70 MPH to at LEAST LA 1, and a few of the US routes around the state should be bumped up to at least 60 MPH.

Ahhhh...TX 49 is a Super 2 designed to be upgraded to a 4-lane tollway; LA 2 is a typical rural highway. NO WAY are they the same, and HELL TO THE NO, they should not be bumped up to anywhere above 55 or 60 mph.

Only fully controlled access highways (freeways and tollways) should be set at or above 60 mph...and only in rural areas.

He is talking about SH49 at the the Texas / Louisiana border, not Loop 49 around Tyler.  Most of rural East TX highways are 60-70mph.  From what I have seen, the wider the shoulder the higher the speed limit.

[agentsteel53]

most two-laners in west Texas are signed at 75!

[kphoger]

While I don't mind lower speed limits on two-laners, I do think that paved shoulders should up the maximum; there's more room to maneuver to avoid accidents.  As should sparse population.  55 to 70 seems like a huge difference, even with one being a 'super 2' and the other not.  As an aside, GMSV doesn't reveal shoulders that are all that wide along TX-49, though its imagery is a few years old.

But, considering the number of curves along LA-2 between the state line and LA-1 and the fact that it skirts a small community along its whopping 4½-mile route, I don't think the lower limit is totally out of line.

[mcdonaat]

I think that at least give LA 2 the benefit of a 70 MPH speed limit until it meets the first community. Take US 71 as an example, it is straight as an arrow from US 190 north to LA 10. No driveways or buildings, wide shoulders, a smooth and flat road... bumping it up to 60 MPH would be the best thing to do, if not 65 MPH. The same can be said about US 65 for most of the route, along with LA 10 between where LA 1 turns off (the old LA 3131) and US 61. Tons of roads need to be studied, but the fact that the state uses the excuse of "we are already doing studies" makes me a little mad. Speed limits should, in theory, relate to the general speed of 85% of the cars on the road. If 85% of people are going down US 71 at 60 MPH, why keep the speed at 55 MPH?

As far as raising the speed limit, it shouldn't be done at a whim. However, we should look at roads that are resurfaced and do a speed study for those roads first. If the traffic goes 60 MPH on a 45 MPH road, and no accidents occur, then raise it to 60 MPH. If you want to see a perfect candidate, look at US 79 Bypass at Homer. Perfectly striped, smooth, with shoulders and ample right of way. In Texas, you would have a 70 MPH highway. In Louisiana, you have 55.

[kphoger]

resurfaced * * * smooth

This is not a reason to raise a speed limit.  What happens as the surface then deteriorates over time?

[mcdonaat]

resurfaced * * * smooth

This is not a reason to raise a speed limit.  What happens as the surface then deteriorates over time?

That's the thing, all roads that I've driven on in other states that have a higher speed limit are smooth and asphalt. Roads don't deteriorate that much here, most of the highways in central or north Louisiana are on hard ground, and only deteriorate due to a lack of resurfacing every 40 or so years. In fact, I drove along LA 107 near Marksville, a road that still has the twin-slab concrete from State Route 30.

[kphoger]

resurfaced * * * smooth

This is not a reason to raise a speed limit.  What happens as the surface then deteriorates over time?

That's the thing, all roads that I've driven on in other states that have a higher speed limit are smooth and asphalt. Roads don't deteriorate that much here, most of the highways in central or north Louisiana are on hard ground, and only deteriorate due to a lack of resurfacing every 40 or so years. In fact, I drove along LA 107 near Marksville, a road that still has the twin-slab concrete from State Route 30.

So you're suggesting they should raise the speed limit on roads that get repaved and then just leave them higher because.....you don't think the pavement will deteriorate again before they get repaved?  This is not a good plan.

[mcdonaat]

resurfaced * * * smooth

This is not a reason to raise a speed limit.  What happens as the surface then deteriorates over time?

That's the thing, all roads that I've driven on in other states that have a higher speed limit are smooth and asphalt. Roads don't deteriorate that much here, most of the highways in central or north Louisiana are on hard ground, and only deteriorate due to a lack of resurfacing every 40 or so years. In fact, I drove along LA 107 near Marksville, a road that still has the twin-slab concrete from State Route 30.

So you're suggesting they should raise the speed limit on roads that get repaved and then just leave them higher because.....you don't think the pavement will deteriorate again before they get repaved?  This is not a good plan.

Noooo... that's not my plan. I was saying that the smoother highways should get raised, the same as the rougher highways get lowered. Not as the pavement gets resurfaced, but whenever the road is redone, and the people do drive faster, then increase it from 55 to 60. If the traffic is low, and the smooth pavement has lasted 10+ years, then raise it accordingly.

[Alps]

Based on my experiences driving in most states, 65 mph is perfectly fine for a rural two-lane road between towns as long as the curvature (and relatedly, sight distance) supports it. 55 is unnecessarily slow for a wide-open road. 75 on a two-lane I don't support, because you just keep adding to the speed differential between adjacent lanes with minimal room for error.

[agentsteel53]

75 on a two-lane I don't support, because you just keep adding to the speed differential between adjacent lanes with minimal room for error.

I've driven out west so many times that I'm used to a lot of roads having very minimum usage.  I've felt safe doing about 95mph on particular two-laners.

but in a typical midwestern state, I agree about 70mph is the safe speed on straight, flat two-laners.

[kphoger]

resurfaced * * * smooth

This is not a reason to raise a speed limit.  What happens as the surface then deteriorates over time?

That's the thing, all roads that I've driven on in other states that have a higher speed limit are smooth and asphalt. Roads don't deteriorate that much here, most of the highways in central or north Louisiana are on hard ground, and only deteriorate due to a lack of resurfacing every 40 or so years. In fact, I drove along LA 107 near Marksville, a road that still has the twin-slab concrete from State Route 30.

So you're suggesting they should raise the speed limit on roads that get repaved and then just leave them higher because.....you don't think the pavement will deteriorate again before they get repaved?  This is not a good plan.

Noooo... that's not my plan. I was saying that the smoother highways should get raised, the same as the rougher highways get lowered. Not as the pavement gets resurfaced, but whenever the road is redone, and the people do drive faster, then increase it from 55 to 60. If the traffic is low, and the smooth pavement has lasted 10+ years, then raise it accordingly.

(1) What is the difference between a road getting resurfaced and being redone?

(2) If the smooth pavement has lasted 10+ years, then you've decided it will not deteriorate after that?

(3) Am I misunderstanding what you mean by smooth and rough?  Because smooth roads eventually turn rough.

[mcdonaat]

(1) Resurfaced is where a road has the pavement removed, and replaced with a newer surface, like is done on Interstates. Redone is where a road is either realigned or straightened, giving the highway a new base and surface.

(2) I know all roads must deteriorate, but under the idea that speed limits can never be given based on the road wear, no road should be above 55 MPH, because they all deteriorate. Timely replacement of the surface is required, and if a brand new surface is laid, people will drive faster, giving that 85% speed range a true meaning.

(3) Smooth roads do turn rough. Some turn rough slower than others. Take Pointe Coupee PR 7 as an example (former State Route 7/US 190). It has had the same concrete surface since the 1930's, when Airline Highway was built. The road has partially washed away due to the force of the Ohio and Mississippi Rivers washing over it, but is in very good condition. Interstate 20, in some spots, was resurfaced only three years ago and already is experiencing potholes. Smooth roads will stay smooth as long as they're built with a strong foundation and proper material. All roads will deteriorate, but some less than others. Concrete > Asphalt.

[kphoger]

(2) I know all roads must deteriorate, but under the idea that speed limits can never be given based on the road wear, no road should be above 55 MPH, because they all deteriorate. Timely replacement of the surface is required, and if a brand new surface is laid, people will drive faster, giving that 85% speed range a true meaning.

No.  Under the idea that speed limits can never be given based on the road wear, 55 mph is no more a magic number than 70 mph.  How did you pick 55 mph?  I've driven on roads so potholed that it's unreasonable to do more than 35 mph.  Simply take out pavement condition from the limit-setting process entirely.  Speed limits should be based on the geometry of the road, amount of cross traffic, hazards, etc.–not pavement condition.

The 85th percentile is one of many techniques that have been used to set speed limits.  I'm not knowledgeable enough about the history there to provide more information.  Mods?  To what extent is the 85th percentile used to determine the safe speed of a roadway?  My suspicion is not very much.