Lane Miles 2

[ouphido]

I am working on calculating the lane miles within a County's jurisdiction. I have seen the definition as being the length of the center line multiplied by the number of lanes. However, I have not been able to figure out if turn lanes or suicide lanes are included in this calculation. Are these lanes omitted as they are not true "travel" lanes?

Thanks

 

[Ron]

They are generally not included; however, there are instances in which their traffic and loading conditions are necessary to know separately. As an example, most turn lanes in high traffic area are subjected to higher instances of braking. If you have an inordinate amount of heavier traffic, these may exhibit more shoving and corrugation than the adjacent through-lanes.

 

[ACtrafficengr]

<soapbox>

Suicide lanes (two way PASSING lanes) were removed from the MUTCD since the '48 or '54 edition.

I suppose you mean two-way left turn lanes? A design feature that can cut crash frequency and severity should not be called a "suicide lane."

</soapbox>

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[ouphido]

You are correct, I do mean two-way left turn lanes. Thank you for correcting me.

 

[civilman72]

Why are trying to calculate this? If it's for state funding (in Colorado this would be HUTF Funds), I believe the amount of turn lanes (particularly for rural roads found in most county jurisdictions) will be neglible when calculating the overall lane miles and therefore can probably be eliminated from the calculation. At least in the county jurisdiction I'm in, the turn lanes would be <1% of overall road miles. Plus, I'm not sure that an auxilary turn lane could be considered a "travel lane."

 

[ouphido]

The County I am in has two cities that receive a portion of the state funding designated for this county. Originally the funding was to be split proportionally based on center line road miles. One city thought this method was unfair and that lane miles would be a better approach. As this is a rural county most roads are 2 lane with very few exceptions (mainly the state roads which are not considered). The city has two-way turn lanes on a few of their roads. Also with less total roads, turn lanes have a more dramatic affect on their total lane miles. This is how the question regarding the auxiliary lanes arose.

 

[msquared48]

Just a thought here. If you are driving in Mexico on a two lane road and the vehicle ahead of you puts on his left turn signal, it is a signal that is it is clear for you to pass him.

Also, there are a lot of head-on and roll-over accidents in Mexico. Gee, I wonder why? It ain't the cartels.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

ouphido...most pavement management systems are based on lane miles rather than centerline miles. After all, the individual lanes feel the loadings, not the "centerline". There can be significant differences in traffic loadings from one lane to another and in different directions. That's why it is important to consider lane miles as opposed to centerline miles.

 

[ACtrafficengr]

NY's state aid to localities proportioning formula does not include auxiliary lanes - just through lanes. I bet your state's Local Technical Assistance Program (LTAP) or Technical Transfer (T2) center knows the answer.

http://www.ltapt2.org/centers/

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[bridgebuster]

AC - thanks for the link

 

[ouphido]

Thank you for the link.

 

[diggerman]

Why are they called "SUICIDE" lanes? That doesn't make any sense. How can you have a two way lane? Maybe I missed 60 minutes last night.

 

[ACtrafficengr]

Been a while since driver's ed?

Two-way left turn lanes are for traffic making mid-block left turns into or out of driveways, or sometimes minor side roads. It lets drivers get out of the way of through traffic, reducing rear-end crashes, and removes the pressure to accept a short gap in opposing traffic, reducing left turn crashes.

That moniker is applied because they seem to invite head-on crashes. If used properly, they don't, since people should be driving slowly or stopped if they are in the lane. However, there always seems to be some yahoo who decides he can use it to get to a left turn a half mile away.

Roadway Type Crash Rate
(All Urban Arterials) (Crashes/Million Veh Mi)


Four-lane undivided 6.75
Three-lane with center turn lane 4.96
Four-lane with median 4.02
Five-lane with center turn lane 4.01

Source: BRW, Inc., study for the Minnesota Department of Transportation, August 1998.

http://www.intrans.iastate.edu/pubs/access/toolkit/16.pdf

"...students of traffic are beginning to realize the false economy of mechanically controlled traffic, and hand work by trained officers will again prevail." - Wm. Phelps Eno, ca. 1928

"I'm searching for the questions, so my answers will make sense." - Stephen Brust

 

[HgTX]

I am amused at the thought of someone getting huffy at misapplication of NONSTANDARD terminology. Was the term "suicide lane" ever in the MUTCD?

Hg

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