Question

Your next project will take place on a two-lane street (each lane is 12 ft wide). The posted speed limit is 45 mph. You will have to close one lane of this street. Write the components/elements of the Temporary Traffic Control (TTC) that you will utilize. Include the minimum required dimension of all components of your plan.

Answer 1

We need to do TTC (temporary traffic control) of a two lane facility, on which one lane is being closed.

we are given 12ft wide lane, and speed = 45mph.

From theory we know that most TTC zones have four main areas

a) advance warning area

b) transition area

c) activity area

d) termination area

the dimensions and locations of the above areas depend on the nature of work going on, the speed limit and characteristics of the road being improved etc.

1) Advance Warning Area - this is when you try to give an advance warning to approaching vehicles that some work is going on. MUTCD recommends that

"On urban streets, the effective placement of the first warning sign in feet should range from 4 to 8 times the speed limit in mph"

so we can place our advance warning sign at 6 * 45 = 270 feet from the start of the work zone

2) Transition Area - We need to manually place cones from a certain distance upstream of work area so that we can channel traffic into the single lane. So the cones need to be arranged like a taper. Guidelines for taper length are as follows

So in our case taper length = 45* w = 12 ft

so taper length =540 feet

our TTC is basically allowing a merging operation to happen.

3) Activity Area - this will contain buffer space, the work space and the traffic space

For a speed limit of 45 mph the longitudnal buffer space maybe assumed to be 360ft

Provide Lateral buffer space of maybe 1 feet.

4 ) Termination Area - here the taper length to be provided should be a minimum of L i.e 540 feet

So overall our TTC zone will look like this