MUTCD lane shifting transition vs. lane taper width requirements
MUTCD lane shifting transition vs. lane taper width requirements
(OP)
Does anyone have any experience with the requirements for a lane transition/offset taper?
I have located the formula in Chapter 6 of the MUTCD which notes that you can use the L/2 for a transition taper where L is the taper length for a merging taper.
I have been told that the L/2 is only applicable to temporary traffic control since this is found in Chapter 6 of the MUTCD for temporary traffic control.
Part 3 of the MUTCD gives the same formula for the taper requirements but does not allow the L/2 to be used for a transition/offset taper. Part 3 of the MUTCD does not make any mention of the difference between a mering taper and a transition/offset taper.
The only reference I have found to the transition/offset taper is that of a transition across an intersection but there is no formula for this transition or maximum allowable offset noted.
Where can I find the length requirements for a permanent lane shifting/offset taper?
SMP
I have located the formula in Chapter 6 of the MUTCD which notes that you can use the L/2 for a transition taper where L is the taper length for a merging taper.
I have been told that the L/2 is only applicable to temporary traffic control since this is found in Chapter 6 of the MUTCD for temporary traffic control.
Part 3 of the MUTCD gives the same formula for the taper requirements but does not allow the L/2 to be used for a transition/offset taper. Part 3 of the MUTCD does not make any mention of the difference between a mering taper and a transition/offset taper.
The only reference I have found to the transition/offset taper is that of a transition across an intersection but there is no formula for this transition or maximum allowable offset noted.
Where can I find the length requirements for a permanent lane shifting/offset taper?
SMP





RE: MUTCD lane shifting transition vs. lane taper width requirements
"For three-lane roadways having a posted or statutory speed limit of 70 km/h (45 mph) or greater, the lane
transition taper length should be computed by the formula L = 0.62 WS for speeds in km/h (L = WS for speeds
in mph). For roadways where the posted or statutory speed limit is less than 70 km/h (45 mph), the formula
L = WS^2/155 for speeds in km/h (L = WS^2/60 for speeds in mph) should be used to compute taper length. Under
both formulas, L equals the taper length in meters (feet), W equals the width of the center lane or offset distance
in meters (feet), and S equals the 85th-percentile speed or the posted or statutory speed limit,
whichever is higher."
RE: MUTCD lane shifting transition vs. lane taper width requirements
For merge tapers it's just L=WS.
Our County DOT uses L=WS for all tapers.
RE: MUTCD lane shifting transition vs. lane taper width requirements
We have been using the formulas that TerryScan referred to.
Intuitively I was thinking that there should be two formulas (for a design speed). I thought that you would have one formula for a lane shift where all of the lanes are shifting together and another formula for a lane shifting/merging into a 2nd lane. Evidentally I was incorrect.
Thank you both again!
SMP
RE: MUTCD lane shifting transition vs. lane taper width requirements
About 8 years ago, when I worked for NYSDOT, we were given guidance from Main Office to use L/2 for permanent shifts. I haven't worked there in 7 years, so they may have changed their guidance since.
Please ask your question on ht
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