 We reviewed the need for traffic control at work sites, examined the traffic control zones, and looked at the standard traffic control devices. Now we want to take a look at some typical applications of work zone traffic control. The various state and local supplements to the manual on uniform traffic control devices provide detailed layouts in addition to those shown in the MUTCD. Unfortunately, it's not possible to demonstrate or illustrate all of the possible applications that you'll encounter in your work. Using your judgment and experience, you can adapt these typical layouts by modifying the dimensions in the various diagrams. Remember, in all situations, the primary purpose of traffic control is to warn and guide the driver while he or she is approaching or passing through your work zone. You are probably most vulnerable during the installation of the traffic control devices. To minimize this hazard, install the devices before work begins. Starting with the first device the driver will see when approaching the area. Then continue installing devices, advancing toward the work area. To evaluate any work zone traffic control, drive through the work zone after all the devices are in place. Difficult as it is, put yourself in the place of the unfamiliar driver, the one who's not anticipating that you're in the roadway. If the traffic control scheme gives the driver the necessary warning and guidance, you and your coworkers will be providing the best protection for yourselves while working on or near the roadway. As soon as the work is completed, remove the traffic control devices in the reverse order of installation, starting with the termination area and proceeding back to the first device installed. A good technique for removing the control devices is to first place them on the shoulder of the roadway and then pick them up in the direction of traffic flow. The best way to illustrate these principles is to show the installation of the control scheme for some common types of operations. In the first example, the work is entirely beyond the shoulder or parking lane. Traffic control will generally consist of flashing vehicle lights and flags. An advance warning sign should be used when the work will interfere with traffic in any way. Now, let's look at work on the shoulder or parking lane. If there is no direct interference with traffic, the motorist should be warned with the sign, shoulder work, as shown. If a shoulder closure is involved, a transition area should be used. The length of the taper should be one-third of the lane closure taper length. In this case, the shoulder width is used for the formula instead of lane width. Remember that the lane closure taper length is the product of the lane width and posted speed limit for speeds over 45 miles per hour. Let's assume a 55 mile per hour posted speed and a 10-foot shoulder. The lane closure taper would be 10 times 55 or 550 feet. The shoulder closure taper is therefore one-third of this or approximately 180 feet. A buffer space should be provided in advance of the workspace. When work is on the shoulder or takes up part of a lane, traffic volumes, types of traffic, this could be buses, trucks and cars, speed and capacity should be analyzed to determine whether the affected lane should be closed. Now, the lane should not be reduced to less than 10 feet. You can consult Part 6 of the Manual on Uniform Traffic Control Devices. When it is necessary to close one lane of a two-lane two-way road, the remaining lane must be used by traffic traveling in both directions. For this example, the speed limit is 55 miles per hour, and the highway is a major arterial route with relatively high traffic volumes. This makes it necessary to use two flaggers and to install the three advance warning signs 500 feet apart. First, install the road work ahead sign for the unobstructed roadway. This sign is placed at least 1700 feet in advance of the workspace. The second sign, one lane road ahead, is placed 500 feet from the first sign. The last sign installed, the flagger symbol, is placed 500 feet from the second sign. The first flagger then assumes his or her station 500 feet from the flagger sign, placing the first flagger at least 200 feet from the beginning of the workspace. The same series of signs are then installed on the side of the roadway on which the work is being done, again starting with a road work ahead sign, 2000 feet from the workspace. A one lane road sign at 500 feet, a flagger symbol at another 500 feet, and finally the flagger 500 feet beyond the last sign. At this time, the two flaggers begin controlling traffic through the one lane section. Next, install a 100 foot taper made up of five or more channelizing devices. A 400 foot buffer space and the workspace are then outlined with channelizing devices, spaced at approximately 100 foot intervals. The work vehicle may then be moved into the closed lane at the end of the buffer space. The 100 foot downstream taper is then installed at the end of the workspace. Finally, the end road work sign is placed 500 feet from the workspace and completes the work zone. As previously emphasized, the best way to evaluate traffic control is to drive through the work zone after all the devices are in place. Now the work activity may begin. After the project is completed and all workers, materials, and equipment are off the roadway, the traffic control devices are removed in reverse order of installation. Remember, a good technique for removing the devices is to first place them on the shoulder of the roadway, then pick them up in the direction of traffic flow. The next example is an urban undivided four lane roadway. The work being done makes it necessary to close the right lane of the roadway. If the left lane were to be closed, the layout would be reversed. If the posted speed is 35 miles per hour with 12 foot lanes, then the required lane closure taper would be 12 times 35 times 35 divided by 60, which equals 245 feet. We'll round it to 250 feet. The first sign installed for the unobstructed roadway is a road work ahead sign. This sign is placed 200 feet in advance of the workspace. The signs for the roadway on which work is taking place are then installed. The road work ahead sign is placed 970 feet before the workspace. The next sign is a right lane closed sign, 200 feet from the road work ahead sign. Then we place a lane reduction transition sign, 200 feet from the right lane closed sign. Now that all of the advanced warning signs are in place, it is recommended that you install an advanced warning flashing error display. This is done to give you the worker added protection while setting up the taper. If there is a shoulder, the error should be placed on the shoulder at the beginning of the taper. If there is no shoulder, it should be placed as illustrated. For this application, the lane closure taper will consist of eight channelizing devices on 35 foot centers for a 250 foot taper. It is a good practice to spot the cones or other devices at the proper spacing on the shoulder and then walk them out into the lane. A 120 foot buffer space and the workspace are then outlined with channelizing devices spaced at two times the posted speed or at 70 foot intervals. The next element installed is a 100 foot downstream taper. The last element installed is the end road work sign, 500 feet from the workspace. Finally, the work vehicle may be moved into the workspace. Again, the best way to evaluate the traffic controls is to drive through the work zone after all the devices are in place. Now the work activity may begin. After the project is completed and all workers, materials and equipment are off the roadway, the traffic control devices are removed in reverse order of installation. The next example will be on a high speed divided multi-lane highway where the work being done requires the right lane to be closed. The first element installed is the advance warning area approximately one and a quarter miles in advance of the workspace. In the previous examples, the advance signs were installed only to the right of the approaching traffic. However, for one-way multi-lane roadways, the advance signs are generally installed on both the left and right sides of the roadway. The first two signs installed are the two road work ahead signs, one and a quarter miles before the workspace on both sides of the roadway. Next, two right lane closed signs are placed one half mile from the first signs, again one on each side of the roadway. Third, a pair of lane reduction transition signs. These signs are placed 1,600 feet from the right lane closed sign. Next, 1,000 feet from the lane transition sign install the second element of traffic control, the lane closure taper. When setting up the taper, it is good practice to place your work vehicle or advance warning arrow display before the start of the taper for added protection. With a 55 mile per hour posted speed and 12 foot lanes, the taper should be 55 times 12 or 660 feet long. For this example, the lane closure taper consists of 13 channelizing devices on 55 foot centers for a total of 660 feet. A 335 foot buffer space and the workspace are outlined by channelizing devices spaced two times the posted speed. For 55 miles per hour, the spacing would be 110 feet. The next element installed is a downstream taper, 100 feet minimum. The last element, the end roadwork sign, is then installed 500 feet from the workspace. Finally, the work vehicle can be moved into the workspace. Again, evaluate traffic controls by driving through the work zone after all the devices are in place. Remember to put yourself in the place of the unfamiliar driver, the one who is not anticipating your presence on the roadway. Now the work activity may begin. After the project is completed and all workers, materials and equipment are off the roadway, the traffic control devices are removed in reverse order of installation. Finally, let's look at mobile operations. Generally, this work uses a moving vehicle train with occasional stops of less than 15 minutes. Mobile operations should be used only during daylight hours and at locations that offer good visibility. When the site distance is restricted approaching a mobile operation on a two-lane roadway, a flagger should be used to protect the workers and to warn the driver. Traffic control for a mobile operation should include warning signs, flags, flashing vehicle lights, channelizing devices, and protection vehicles. Arrow displays should also be used, except on two-lane roadways. Despite the brevity of short-term operations, certain traffic controls are necessary. In urban areas, the work vehicle may be used for warning if it's equipped with flashing lights, rotating beacons or flags. When it's necessary to enter or leave a manhole, workers should always station a work vehicle upstream from the manhole. Materials or equipment should be stored away from the manhole opening. These principles presented apply to utility work zones and are just as mandatory as those in roadway work. We have briefly reviewed a few examples of layouts under a number of different conditions. This small number cannot nearly begin to address all the possible situations that you'll encounter. You'll often be called upon to develop your own traffic control plan, providing safety for both workers and drivers. While this task may be time-consuming, it is part of your responsibility that can never be set aside because of the urgency to get on with the job.