 During snowy winter months, motorists may encounter hazardous roadway conditions. Particularly, this might occur when there are snow removal operations underway. This presentation describes these operations and addresses maintenance remedies to apply in post-snowstorm cleanup. The driving public expects clear streets and highways on a year-round basis, even during periods of heavy snowfall. Significant manpower and financial resources are expended annually for snow and ice control programs by state, county, and municipal governments. According to a Transportation Research Board's special report, state and local governments spend over $1 billion annually for snow and ice control. This presentation, primarily, is for state and district highway maintenance engineers responsible for managing and operating snow and ice control programs for state governments. However, the remedies described can be applied to any region of the USA. The project goal is to identify actions that can be implemented with existing manpower and equipment budgets. Snow and ice control programs typically are divided into two parts. One, programs for emergency snow removal to clear traffic lanes, which takes place during and immediately following a snowstorm, and two, programs for post-snowstorm cleanup, which takes place between snowstorms after emergency snow removal has been completed. Emergency snow removal is necessary for clearing or opening highway travel lanes. Hazardous conditions may be created or overlooked during the removal operation because of time constraints involved in emergency snow removal. Once a roadway network is reopened to traffic, maintenance crews perform post-snowstorm cleanup in preparation for subsequent storms. Cleanup includes removing snow that has accumulated adjacent to shoulders in order to make more room for additional snow. Cleanup also entails clearing snow from the high side of super elevated curves and ramps to prevent refreezing of melted snow. Cleanup means removing accumulated snow from bridge parapets and guardrails to prevent vehicle ramping accidents and also includes removing snow piled at intersections. Removing snow also from interchanges improves sight distance, thereby reducing the chance of severe collisions. Restoring roadside features to full operational effectiveness as soon as possible after a snowstorm is of the highest safety priority. State snow and ice control policies and guidelines address some, but not all, safety issues. State Highway Maintenance Engineers report that snow-related hazards during post-snowstorm cleanup operations are common and need to be remedied. This study identifies snow and ice removal hazards and it groups them according to their relative importance, most serious, serious, and important. A hazard ranking is based on the risk or the possibility of an accident occurring, the severity of an accident that could result, the ease of correcting the hazard and driver exposure to the hazard. All identified hazards can have serious adverse consequences to winter traffic safety. The four hazards ranked most serious should receive high-priority treatment in post-snowstorm cleanup operations. The most serious ranked hazards are snow accumulation on super elevated ramps and sharp curves, snow or ice accumulation at bridge parapets, railings, and curb areas, traffic vehicles colliding with snow removal vehicles or equipment, and snow left piled at intersections, interchanges, and curves where motorist vision is obstructed. Snow left to accumulate on the high side of curves can melt and re-freeze, creating sheets or patches of ice on the once-cleared road surface. This is called freezeback. It usually occurs when piled snow is melted by de-icing chemicals or solar heating. This allows moisture to run back across the previously cleared driving surface. This moisture then freezes in the cold of early evening, which is especially hazardous because it is unexpected and not seen by motorists. Super elevated curves, ramps, and bridge decks that have a flat cross-section especially are susceptible to freezeback. Snow stored on the high side of super elevated curves should be plowed or winged over the high side edge of the shoulder line and ditch. This helps prevent drainage of snow melt onto pavement. Widening the cleared area on curves alleviates the problem of reducing sight distance, resulting from large piles of snow left in the middle of the curve. On super elevated bridges and ramps, snow should be plowed to the low side edge of the shoulder. This is best done during off-peak periods of traffic, with plows working in tandem to move the snow across several lanes simultaneously. The second most serious ranked hazard is snow or ice accumulation at bridge parapets, rails, and curb areas. Many times during emergency snow removal on bridges, snow is plowed against parapets and rails. If this snow is not removed, it becomes hard packed. If piled and left at two-thirds the height of the bridge parapet or rail, it will create high potential for vehicle ramping accidents. The most critical areas on a bridge are the parapet, rail, or curb along the south side of an east-west oriented bridge. Because that side is always shaded, melting is delayed. Safety shaped bridge parapets, regular bridge parapets, and open pipe bridge rails are subject to vehicle ramping accidents, which can result in fatal injuries. Light snow can be pushed off short bridge decks with a plow, but plow speed must be reduced while working on overpasses to prevent throwing snow over parapets or through railings onto the roadway, railroad tracks, or buildings below. Plowing in tandem can be used to clear an entire bridge deck, including railings. Plowing in tandem is most safely accomplished under well-lit conditions, and when traffic is light. A moving barrier, such as a police vehicle with revolving lights, can be used to prevent motorists from passing the convoy of plows. After a snowstorm, when visibility again is relatively good, use warning lights to alert motorists. Remove snow and ice as completely as possible on bridge parapets, rails, or curbs. If the removal is incomplete, when temperatures rise to cause melting, moisture from remaining snow may run back across the pavement. With a temperature drop, a freeze-back condition is created. An extreme temperature increase can cause unsupported snow accumulation to collapse and spill onto the travel surface. Remove all snow accumulations either by blowing, hauling away, or pushing snow to the end of the bridge and overfill area. The potential for vehicles colliding with snow removal equipment is another most serious ranked hazard. Differences in operating speed between snow removal vehicles and traffic vehicles and poor visibility created by blowing snow creates the high potential for collisions. Many fatalities have been caused by rear-end collisions with plows. Head-on accidents have occurred when plows were operating near the centerline facing oncoming traffic. Keep in mind that vehicles return to their original operating speeds as soon as roadways are cleared and reopened. This speed shift adds to hazard potential at a site. Snow plow operators complain about motorists' driving habits during removal operations. Because motorists generally do not understand snow plowing operations, frequently they misjudge width, length, and speed of the plowing vehicle. Impatient motorists often speed, tailgate, or try to pass plows. Sometimes, while attempting to pass, motorists misjudge a plow's operating speed and hook their rear bumper onto the plow blade. To reduce potential collisions with snow removal vehicles, high-intensity lighting devices visible to other drivers both in front and to the rear, even through blowing snow, are recommended. Lights to indicate plow width are also recommended. For example, side clearance lights can be mounted at cab height and swivel into place for snow removal operations. The New York Throughway Authority has been using flashing arrow panels on its vehicles to alert motorists. All of its plows have been wired to enable lighted arrow panels to be interchanged between vehicles. The traveling public needs to be better informed about the actual difficulties there are in driving, handling, and maneuvering snow plows and other equipment. Public service announcements have been used for educating motorists on how to drive during winter conditions using the theme of give them room. The fourth most serious ranked hazard is obscured visibility due to snow piled at intersections, interchanges, and curves. Snow left piled near intersections can affect a motorist's ability to see oncoming vehicles at intersecting roads. These piles of snow also block an oncoming motorist's view of cars at intersections. Unsignalized four-lane intersections should be cleared first. In interchange on-ramp areas, piles of snow can hide merging vehicles and vehicles stopped at crossroad intersections. There is a location near the gore point of on-ramps where entering vehicles can be hidden by snow piles and cannot see mainline vehicles. High-speed accidents resulting in severe injuries can occur if these intersecting vehicles collide. The following five potential hazards are ranked as serious. Snow or ice on guardrails, improper alignment of snow plows, stalled or abandoned vehicles impeding snow removal operations, lack of snow storage areas at narrow medians, shoulders, and gores, and snow left on barriers. These hazards, although serious, should be treated after the higher-ranked most serious hazards are remedied. Unsafe conditions may result if snow or ice is left on guardrails. These include possible melting and refreezing, reduced effectiveness of the guardrail section due to piled snow, and snow drifting onto a clear road. Snow or ice accumulation along guardrails may result from drifting snow or plowing operations. This is more of a hazard on freeways than on other roadways because of the greater lengths of guardrail, traffic volumes, and vehicle speeds. To prevent long-term snow accumulation around guardrails, plowing out to the guardrails is recommended as soon as possible after a road is reopened to traffic. To prevent drifting and snow melt, clear snow from the shoulder inside of guardrails and near the start of guardrail sections. Guide stakes or delineators used at guardrail ends help plow operators locate guardrail lengths, even when they are completely covered with snow. Improper alignment of snow plows may cause traffic following the plowed path to drive off the traveled way. Improper alignment also can decrease usable lane width. This serious hazard arises from large snow plows being unable to negotiate the small radius curves of highway ramps. Also from plows wandering off the pavement area because roadway edges are not delineated. Or from inattention of the snow plow operator, who often works long hours until the roadway system is in acceptable operating condition. Guide stakes are used to delineate the edge of pavement and also to help plow operators maintain proper plow alignment. Within interchanges, guide stakes should be installed at 50-foot intervals. Guide stakes can be spaced farther apart between interchanges and on rural routes. To preclude the costs of an annual installation removal, some states leave them in place year-round. Stalled or abandoned vehicles impede timely emergency snow removal and cleanup operations. This is ranked a serious hazard. Severe snowstorms occurring at rush hour in urban areas create the worst problems because of the higher volumes of traffic using them. In rural areas, stalled vehicles can force highway agencies to close roads. Blowing snow particularly is an acute problem in areas where high winds cause drifting. Tractor-trailer combination trucks are susceptible to run-off-the-road accidents and present the biggest problem in clearing roadways because they are difficult to remove. To help prevent the problem of stalled vehicles during heavy snow, use public service announcements to warn people to stay home or to exit the road and sit out the storm. Use of commercial tow trucks for the removal of stranded vehicles should be part of a plan to support snow removal operations. Likewise, commercial snow removal vehicles may be used in a plan to supplement normal plowing operations. Lack of snow storage areas at narrow medians, shoulders, and gore areas is another serious hazard, especially when snowfall has been heavy or when storms occur in close succession. When piled snow melts, the run-off can re-freeze and cause localized icing. Piled snow also can obscure vision. It can even collapse onto the travel way during melting conditions. On multi-lane highways, to prevent snow accumulation in narrow medians where there is less than 20 feet of storage width or raised concrete median barriers are present, allow the snow in tandem from the left shoulder fully across the roadway to the right. Otherwise, snow will have to be loaded onto trucks and hauled away. Use wing plows to create extra storage area on shoulders. In gore areas, a motor grater or hydraulic front-end loader should be used to remove snow. In highway gore areas, excessive sanding and salting should not be done on bare pavement. They can act like ball bearings, causing vehicles to skid, to strike signs, and other appurtenances. The pavement may require sweeping. Snow and ice piled against roadside or median concrete safety-shaped barriers, especially in areas of frequent and heavy snowfall, is another serious hazard. As with bridge parapets and rails, snow piled at two-thirds the height of the barrier changes its shape and creates a vehicle-ramping hazard. The hazard is compounded in areas where vehicles can strike barriers at angles greater than 15 degrees, such as on the inside of curves and in wide medians. That side of the barrier facing the sun may be clear of snow, but the shaded north-facing side may contain packed snow. Normal plowing procedures dictate removing snow from the lower face of a safety-shaped barrier, but not removing packed snow that forms a ramp on the upper face. It is best to clear accumulated snow from barriers before it reaches two-thirds of the barrier height or hardens. In Brown County, Wisconsin, a heavy rubber blade attachment, as shown here, aids in clearing snow away from barrier faces. This rubber plow attachment was designed to scoop snow out away from safety-shaped barrier faces. Attachments can be made for either the left or right side of a snow plow blade. The solid rubber attachment is one-and-one-half inches thick heavy rubber belting material. The cost is about $250, and the device should last two or three years if used properly. Another device Brown County uses to remove snow from safety-shaped barriers is a metal attachment for snow blowers mounted on front-end loaders. Several important snow and ice accumulation hazards also are remedied during post-snowstorm cleanup operations. These important ranked hazards do not require immediate attention except where obvious problems exist. Some of these hazards are associated with drains, culverts and channels, snow or ice windrows, shallow cut areas, and at-grade railroad crossings. Other important hazards to be considered include snow accumulations at pavement obstructions, such as curbed and raised areas, snow or ice obscured highway signs, and snow and ice-covered impact attenuators. Accumulations of snow, ice, or debris at clogged drainage channels, culverts, and grade openings can be hazardous. But when snow melts on the pavement, pools of water can be created which also may freeze. Heavy rains occurring before a snowstorm can increase this hazard. Arrows painted where they will not be obscured on barriers, parapets, or pavement indicating presence of drains, aid in locating drains when they're covered by snow. For example, the New York Throughway Authority marks drain locations, even giving the distance from edge line to the drain. When clearing bridges, check drains to see that they are clear. Clogged drains may require thawing out and hand cleaning. Drainage problems at culverts are more common in areas with a deep frost depth, where ice remains in the culvert. In the spring, rain and melting snow can build up on the roadway and re-freeze, creating slippery spots. A steam generator can be used to melt the ice in this and other areas. Clear drainage channels have drifted or accumulated snow that have a history of snow and water backup. In anticipation of thawing weather, clear these areas with a hydraulic excavator or similar piece of equipment. A snow or ice windrow prevents water from running off the pavement, especially in hilly areas. Breakout openings in the windrow to permit drainage. Snow or ice windrows may build up at gore areas of highway on-ramps and at roadway intersections. These are important ranked hazards that present an unexpected obstacle to drivers. To mitigate a windrow hazard, adjust plow speed and moldboard angle. Plows operating singly should continue plowing until snow and windrows have been moved all the way to the right. If more than one plow is used, plowing activities should be coordinated so that the second plow is in tandem behind the first, on both the mainline and ramps. Snow blowing or drifting across a road can block travel lanes because there may be a lack of storage in cut sections. This is another important ranked hazard. This hazard is aggravated by successive snowstorms over a short period. Roads built perpendicular to the usual wind direction also have definite drifting problems. Remedies to blowing or drifting snow include installing snow fences, winging back, benching drifts, using a snowblower when a shallow cut is full, and loading and hauling away snow. A warning vehicle is needed to alert approaching motorists that roadside cleanup is in progress. Snow or ice pushed onto at-grade railroad crossings is another important ranked hazard. Once snow, ice, or aggregate gets into flanges or rails, it's difficult to remove and can cause derailments. To alleviate this hazard, empty the plow along the shoulder in advance of an at-grade railroad crossing. This avoids carrying snow or slush containing aggregates onto the tracks. Approaches to railroad crossings should be treated to prevent slippery conditions, but chemicals must not be spread on the track area itself. Plow operators must use extreme care when working around railroad tracks because the extra length of their vehicle and noise of operation can prevent their hearing and approaching train. Adjusting the angle of the plow so that it is not parallel to the angle of the railroad track will prevent the plow blade from dropping into track channels. Also, care should be taken to not plow snow onto railroad tracks from overhead bridges. Pavement obstructions, such as curbs, raised islands, rumble strips, delineators, buttons, joints, and manhole covers, especially at traffic-channelized areas, can prevent complete snow and ice removal. Remove snow from these obstructions before it has a chance to melt, spread on adjacent pavements, and re-freeze. In areas of heavy wet snowfall and high winds, snow-obscuring highway signs is another important ranked hazard. Snow thrown by plows also can adhere to signs. An unsafe condition exists when motorists cannot see a sign legend, especially those on warning and regulatory signs. Sign posts can be struck to shake snow loose. Fortunately, snow adhering to signs usually melts and slides off when the sun comes out. In heavy snow areas where drifting snow covers signs, dig back an area in front of the sign, especially for those in critical places. Still another important ranked hazard is snow or ice accumulation on impact attenuators. The attenuator may become jammed with snow or ice from emergency removal operations. An out-of-control vehicle can climb snow-covered attenuators and impact the hazard it was to be protected from. Impact attenuators operate well under most adverse winter conditions, when snow and ice accumulation does not hinder operation. To avoid cracking sandbarrel attenuators during snow cleanup, carefully remove snow with a plow or other equipment. When filling sandbarrels, mix 20 to 25 percent salt with the sand to prevent freezing. A special hazard category exists in mountainous regions. Where there are sustained steep roadway grades, there is high potential for runaway trucks. Truck escape ramps are designed to safely stop these vehicles. In the winter, however, a hazard develops if ramp approaches have not been adequately cleared of snow during emergency snow removal operations. Windrows of plowed snow left at entrances to escape ramps form hazardous barriers that can cause runaway trucks to become airborne, thereby increasing the severity of runaway truck accidents. Clearly define the approaches to truck escape ramps, so that runaway trucks have a wide enough clear entrance to the arrestor bed. The arrestor bed itself becomes less effective in slowing trucks if melted snow and ice are allowed to re-freeze. The arrestor bed should be cleared and its crusty surfaces broken up. A small tractor can be used to clear snow from the arrestor bed. The tractor can break up crusty bed surfaces with a rear-mounted fork attachment. A four-step procedure is recommended for determining priorities in post-snowstorm cleanup and may be made a part of any comprehensive snow removal plan. The four steps in this procedure are, one, obtain an inventory of existing safety features. Two, consider hazard categories. Three, determine remedies. And four, develop local cleanup priorities. The procedure recognizes varying conditions, geography, time of year, equipment available, and other factors specific to each state maintenance department. In implementing the noted four-step procedure, it is important to give support to the maintenance engineers. In determining remedies for most serious and serious hazard categories, the use of experience and engineering judgment should be exercised. More information concerning the hazard categories and remedies described in this presentation can be found in the Federal Highway Administration Technology Sharing Report, titled Safety Restoration During Snow Removal Guidelines.