What Does a Flashing Yellow Arrow on a Traffic Signal Mean?
In December 2009, after extensive testing, the Federal Highway Administration authorized use of flashing yellow arrows nationwide. A study conducted by the National Cooperative Highway Research Program determined that drivers had fewer crashes with flashing yellow left-turn arrows than with traditional yield-on-green signal configurations.
Flashing yellow arrow traffic signals feature a flashing yellow arrow in addition to the standard red, yellow and green arrows. When illuminated, the flashing yellow arrow allows waiting motorists to make a left-hand turn after yielding to oncoming traffic. Otherwise, the new traffic signals work the same as traditional signals.
What the Arrows Mean
Read the Text below or download the PDF HERE
Alkali-Silica Reaction (ASR)
ASR Definition: A Process in which silica (found in aggregate) in the presence of moisture, is broken down by alkalis (found in cement) produces an expansive gel. The expanding gel creates tensile forces, causing the concrete to crack. The cracking then allows more water to infiltrate into the concrete creating more gel, more expansion etc. Ultimately the concrete fails or disintegrates.
Timeline: ASR is present in some NDOR concrete constructed between 1985 – 1998.
National Impact: ASR has been documented in 36 of the 50 States.
Current State of ASR in NE:
Existing Concrete – NE continues to resurface or rebuild affected concrete pavements.
NOTE: Rumble strips are used on the sides of highways in Nebraska and across the United States as a safety measure to alert drivers when they are near the edge of the road surface. Centerline rumble strips are explained below.
Have you ever wondered about the marking, or striping, on Nebraska's Highways?
Purpose...Highway Markings provide guidance and information for the motorist. Major types of highway markings include pavement and curb markings, object markers, delineators, colored pavement, and barricades. In some cases markings are used to supplement other traffic control devices such as signs and signals. Some of the more common highway markings include:
Miles & Miles...There are 9,959 miles of highways on Nebraska's state highway system, however a number of roads on the state system, such as the Interstate, have several lanes. This means that NDOR has approximately 22,634 lane miles of highway to stripe.
Durability...Highway markings may last from several months to several years, depending on the amount of traffic. NDOR has 6 crews, state wide, that re-stripe the various highways on a regular schedule. The schedules vary with the areas and the highways. Interstate 80, in the Omaha area is re-striped three times a year or as needed. Highways, in other areas, are re-striped every other year, or as needed.
Materials Used...The Department is using preformed tape markings and plowable pavement markings on certain areas of Interstate 80. The majority of traffic paint applied by state crews is water-based traffic paint, along with a small amount of solvent-based traffic paint used in the Omaha area.
We use an average of 300,750 gallons of white paint and 145,000 gallons of yellow paint each year re-striping highways. We also use small glass beads which are applied directly onto the surface of the wet paint for added visibility. NDOR applies approximately 1,692,000 pounds of beads each year, not including beads used in highway striping that is contracted out each year. Numerous quality control tests are performed on each type of paint used, as well as on the glass beads which are added to the paint. These tests are to determine both the durability and reflectivity of both the paint and the glass beads.
What are the stocking cap like things found sometimes on poles beside the highways?
Motorists on Nebraska's state highways may see WINDSOCKS at various locations. The windsocks were put up to indicate wind strength and direction for truckers and other people driving high profile vehicles.
There are currently 16 windsocks on Nebraska's highways...12 at various locations along Interstate 80, 1 on US Highway 77, south of Lincoln, 1 on Highway 20 in central Nebraska, and 2 on Highway 71, north of Scottsbluff.
The windsocks have been up since 2002, and we have received favorable comments from the trucking community on their usefulness.
This is called dowel bar retrofitting.
Background: As vehicles travel down the highway, the weight of the vehicle load passes from one concrete panel to the next. In older highways, dowel bars (steel rods) were placed at transverse joints along the road to help transfer the weight of vehicles from one panel to the next. Since many of the early dowel bars corroded and needed to be replaced, their use was discontinued. However, without the dowel bars, weight load transfer was dependent on the strength and cohesion of the concrete at the joint, and the support of the road bed. Over time this joint can break down and fail to provide a good load transfer. When this happens the joint begins to displace, or fault, and provides the “thump-thump” sound you may hear while driving.
We would then have to grind the pavement to again provide a smooth ride. This would last approximately 6-8 years and then the “faulting” would return. Faulting can also have undesirable effects. Also, joint seals tend to open up and allow moisture to enter. Moisture damages and weakens the sub grade, allowing the loss of sub grade material that causes edge cracking, pot holes, and settling or cracking of the adjacent shoulder.
Solution: NDOR began using epoxy coated dowel bars about four years ago to alleviate this problem. The epoxy coating retards the effects of moisture and chemicals on the steel bar. The dowel bars are installed by cutting slots into the existing pavement, three in each wheel path, a dowel bar is placed in each slot, and the slot is filled with high strength non shrink grout. The area is then ground smooth and the joint is resealed. The retrofit also prolongs the life of any resurfacing that might have to be done at a later date. NDOR has completed about a dozen retrofit projects over the last four years and plans to do three to four retrofit projects each year in coming years.
New Construction: Epoxy dowel bars are now used in new construction. They are put in place prior to paving and are not visible once the paving is complete. The installation of dowel bars extends the life of the pavement, improves the ride quality and is less expensive than the maintenance activities that would be required without them.
What & Why: Most motorists have, at one time or another, driven on a milled road. Milling is the process of removing high spots, bumps and ruts from the road’s surface for a more even surface, and is done for the safety of the driving public. It can be done as a stand alone project or in connection with a resurfacing project. Milling promotes proper drainage to prevent standing water and/or ice from building up on the road which can cause hydroplaning or loss of directional control.
Personnel: The Department of Roads has a four member crew that specializes in fine profile milling for state maintenance projects, and if needed, they can be any place in the State within 48 hours. The crew coordinates with each of NDOR’s eight districts to determine what milling projects are needed, and a schedule is arranged. The milling crew works on shorter maintenance projects. Longer projects and milling connected with resurfacing projects are frequently done by contractors. While in each district, the milling crew works with the maintenance crew from each supervisor’s area. The maintenance crew provides the traffic control, water trucks, broom operator and trucks to haul the millings to stockpile sites. The millings are used to build up shoulders, fill washout and occasionally for blade patching if the material is good enough. Some also may be used in the yards or on gravel/dirt roads for sub-grade material.
Facts & Figures: The State’s current milling machine is approximately 6 years old. It has a 7’ 2” drum with approximately 453 carbide bits. The bits will last from ½ day to several days depending on the type of surface being cut. The machine can cut anywhere from 1/4” to 10” deep with most projects being cut ½ to ¾ inch. The cutting is followed by an armor coat to reseal the road surface. On average the crew will mill 1 ¾ million to 2 million square yards a year.
What are those people doing when they watch traffic and look like they're keeping track of vehicles? How do you collect all your traffic volume data? Is automation used, and how?
The Nebraska Department of Roads (NDOR) Traffic Analysis Unit uses BOTH people and automation to collect traffic information. That info is developed into classification data used by planners, engineers, and designers. Traffic forecasts can be developed from it, and the data helps cities and other public agencies when they do their planning.
Automated Traffic Counts, done with a portable machine can be done at thousands of locations each year, at any time of the day or week, and are the least expensive on a per count basis. However, they are somewhat limited as to what they can count. Most count only volume, with only some able to give info on the classification of traffic by vehicle type.
Manual Classification Counts are done at approximately 150 locations around the state per year. They usually occur on weekdays, and are usually at intersections, to provide greater vehicle info. Counts are taken for 8 hour periods and the sample counts are adjusted to represent 24 hour annual average volumes. However, an advantage of the Manual Count is that the operator can also see what types of vehicles are counted...motorcycles, passenger cars, school & city busses, trucks and other types of multi-axle vehicles. In all, vehicles are classified into one of 14 different vehicle categories, so even though the time frame for the manual count is limited when compared to Automated Counts, more precise classification info can be gathered.
Are there any plans to reopen the West Center collector-distributor (CD) road to the Pacific Sreet exit ramp?
A determination was made by NDOR that this connection from West Center Road to Pacific Street was causing traffic delays and congestion on the I-680 corridor and safety concerns on the northbound West Center Road on-ramp.
Therefore, this has been closed permanently to eliminate back-ups, and to smooth traffic flow. However, the ramp will still be utilized for emergency traffic handling at times when mainline northbound I-680 may be blocked.
NDOR is continuing to monitor this area, and is studying this segment of I-680 from I-80 to West Dodge Road for improvements.