Design Guide for Addressing Nonrecurrent Congestion (2014)

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134 5 EXAMPLES OF DESIGN TREATMENT INSTALLATIONS Several of the treatments described in Chapters 3 and 4 have been implemented, in varying degrees, by highway agencies. They have not always been implemented for the specific purpose of reducing nonrecurrent congestion; however, lessons can still be learned from the agencies’ experiences with design, construction, cost, benefits, and challenges. This chapter presents several examples of treatment implementations that were documented in the literature, described in news articles, or identified in inter- views with highway agency staff. Although detailed information was not available for inclusion in this report for many of these implementations, the purpose of this chapter is to provide the reader with enough information to follow up with the agencies who have implemented treatments like those being considered by the reader, or who have attempted to address congestion issues similar to those the reader is addressing. EMERGENCY CROSSOVERS The Illinois Department of Transportation (DOT) undertook a project in 1997 to make improvements to I-55 (Stevenson Expressway) in Chicago. The design draw- ings for this project included a detailed plan for an emergency turnaround opening in the median to be used in conjunction with alternating shoulders. The 20-ft-long median opening is located at a place where the alternating shoulder transitions from a westbound left shoulder to an eastbound left shoulder. A pavement marking line and diagonal hashes have been used to designate the shoulder. “No U-turn” signs have been placed at either end of the median opening to discourage the use of this emer- gency turnaround by general traffic. The cross section of the roadway consists of two 11.5-ft westbound lanes, an 8.2-ft left shoulder that alternates between the westbound and eastbound direction of travel, a 2-ft-wide concrete median with a 600-mm glare screen, and two 11.5-ft

135 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION EXAMPLES OF DESIGN TREATMENT INSTALLATIONS eastbound lanes. A guardrail is located along the outside edge of the rightmost lane in both directions of travel. GATED MEDIAN BARRIERS Texas In the late 1990s, several gated median barriers were installed near Houston, Texas, on the following roadways: • IH-45 North (four gates) • US-59 Eastex (five gates) • US-59 Southwest (11 gates) • US-290 Northwest (eight gates) The Texas DOT prefers the manually operated gates over the automated gates, pri- marily because of the rather infrequent use of the gates. When left closed for extended periods of time, the automated gates tend to lock up and not function correctly, but the manually operated gates have not experienced these problems. Because the Houston area freeway system has frequent interchanges and a com- prehensive system of frontage roads, the gates were not installed to be used by emer- gency responders to decrease response time. Rather, their intended main function was to reroute traffic in response to major incidents. However, the gates have rarely been used for this purpose. One complicating reason for this infrequent use is that the gates are along a section of roadway that has a center contraflow lane for carpools and buses only. The contraflow lane allows inbound traffic during the morning peak period and outbound traffic in the evening peak period. Because Texas DOT wants to encourage bussing and carpooling by maintaining good operation in the high-occupancy vehicle (HOV) lane, they are hesitant about opening the gated median barriers and disrupting the center contraflow lane, even during incidents on the mainline. Additional gated median barriers have not been installed since 1999. Michigan In 2008, the Michigan DOT installed gated median barriers as part of an improve- ment project on I-75 between Dixie Highway and Birch Run Road near Bridgeport, Michigan. This project involved widening I-75 and eliminating the existing mainte- nance crossovers. Because the section between Dixie Highway and Birch Run Road is over 8 mi long, gated median barriers were installed to maintain access for emer- gency and maintenance personnel. Training courses and instructional literature for the appro priate use of these gates were offered to local fire departments and state, county, and local police departments. Two semiautomated gates were installed in the concrete median barrier along this section of I-75. These gates can be opened by users who enter a code on an electronic keypad. The gates have a manual override if the electronic control should fail. The purchase and installation of each gate added approximately $125,000 to the cost of the project.

136 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION There are few recorded instances of the gates being used by emergency personnel to decrease response time. Part of the reason for the low usage rate is that this section of roadway lies between two law enforcement jurisdictions, making it difficult for dispatchers to determine which direction officers will be coming from. Another chal- lenge is the frequent incorrect reporting of crash direction to emergency personnel. Michigan DOT plans to install cameras along this section of freeway to assist in pro- viding emergency personnel with better information. These gates have been used by the fire department, although the large turning radius of the fire trucks makes their use difficult. Because fire trucks need additional turning space, traffic must remain clear of the inside lanes in both directions of travel, and accomplishing this without law enforcement on site to close the lanes makes this maneuver even more difficult. For these reasons, the median barrier gates have not often been used to reduce the fire department response time. Another difficulty with these gates has been the corrosive effect of snow and ice on the moving parts of the gate. Ice, salt, sand, and other debris accumulate on the gate and can damage the gears, motors, and other internal components. Currently, exten- sive maintenance is required to keep the gates operational, though Michigan DOT is working with manufacturers to improve the resilience of these gates in harsh winter conditions. Energy costs for the operation of these gates are approximately $25 per month per gate. EXTRA-HEIGHT MEDIAN BARRIERS A project was completed by the Georgia DOT in 2005 to raise the height of a median barrier along a 7-mi section of I85 in Union City, Georgia. The total project cost was $39.7 million, including 7 mi of road reconstruction of outside lanes with associated patching and rehabilitation, an updated guardrail, updated bridge side barrier, expan- sion of the shoulder to 12 ft in width, and the addition of a glare screen to the existing center median barrier for the total length of the project. DRIVABLE SHOULDERS The Minnesota DOT has retrofitted several existing expressways and freeways to allow buses to drive on the shoulder. These drivable shoulders, known as bus-only shoulders, consist of segments ranging from 0.3 to 9.0 mi in length. The segment lengths vary depending on the location. The bus-only shoulders are operational whenever traffic in the adjacent travel lanes is moving at speeds less than 35 mph. Buses may not travel more than 15 mph faster than the mainline, and the maximum speed allowed on the shoulder is 35 mph. Bus-only shoulders are typically located on the outside shoulder, and the segment is signed as such. Signs warning of buses on shoulders are placed at intersections within the segment to alert drivers entering the roadway to watch for buses on the shoulder.

137 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION Construction costs for these projects vary depending on whether a shoulder is being converted or is part of a new construction project. Table 5.1 indicates differ- ent scenarios and the associated costs for implementation on a freeway or express- way. Operating and maintenance costs include the additional cost of snow and debris removal in these areas. There are also increased costs to repair. ALTERNATING SHOULDERS The Illinois DOT undertook a project in 2001 to make improvements to the south- bound lanes of I-57. Part of the traffic control plan for this project involved shifting the southbound traffic to the northbound lanes via a median crossover and using the northbound lanes to carry both northbound and southbound traffic. The Illinois DOT determined that two lanes were needed for each direction of travel. However, because providing a four-lane cross section on the existing roadway did not permit adequate shoulder space in both directions, the decision was made to implement alternating shoulders. During the project, the cross section of the roadway comprised two 11.5-ft south- bound lanes, a 2-ft-wide concrete median with a 600-mm glare screen, a 6.5-ft inside shoulder that alternated from one direction of travel to the other, and two 11.5-ft northbound lanes. A guardrail was located along the outside edge of the rightmost lane in both directions. In the transition section between the southern and northern ends of the project, which was about 160 ft long, the concrete median was gradually shifted to eliminate the northbound left shoulder and provide a southbound left shoulder. This configuration allowed for a four-lane cross section in the existing roadway width, while intermittently providing a shoulder refuge area for both directions of travel in case of a crash or vehicle disablement. TABLE 5.1. COSTS ASSOCIATED WITH IMPLEMENTING BUS-ONLY SHOULDERS Condition Cost Plus Signing and Striping Shoulder width and bituminous depth are adequate. Catch basins do not need adjustment. Signing and striping are only requirements. $1,500 per freeway mile $2,500 per expressway mile Shoulder width and bituminous depth are adequate. Minor shoulder repairs and catch basin adjustments are needed. $5,000 per freeway mile $5,000 per expressway mile Shoulder width is adequate, but bituminous depth requires a 2-in. overlay. This assumes shoulder and roadway can be overlaid at the same time. $12,000 per freeway mile $12,000 per expressway mile Same as above but adjacent roadway is not being overlaid. Shoulder must be removed, granular base adjusted, and increased bituminous depth replaced. $80,000–$100,000 per mile Shoulder width and depth replacement are required. $42,000–$66,000 per mile for both freeway and expressway Installing a 12-ft shoulder rather than a 10-ft shoulder in a new construction project. $30,000 per mile for both freeway and expressway

138 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION EMERGENCY PULLOFFS The Minnesota DOT made improvements to I-94 in Minneapolis in response to increased traffic demand after the I-35W bridge collapse. The improvements to I-94 included adding a lane to carry the additional traffic while the I-35W bridge was re- paired. After the bridge repair was completed, a project was undertaken on I-94 to build an acceptable permanent configuration while keeping the additional lane that was constructed. Because some sections of the roadway were left with limited shoulder width, emergency pulloffs were constructed at multiple locations along the roadway to accommodate such incidents as vehicle breakdowns and crash investigations. The length of these emergency pulloffs was generally 150 to 200 ft. The cost of constructing a single pulloff was $75,000, unless a retaining wall was required. The con struction of a retaining wall added $150,000 to the cost of constructing a vehicle pulloff. Con- struction of these pulloffs was completed in the summer of 2010. CRASH INVESTIGATION SITES The Georgia DOT installed approximately 50 or 60 crash investigation sites (or ac- cident investigation sites, as they are called within Georgia DOT) in the late 1990s. These sites are 12-ft-wide shoulder extensions paved with asphalt. They are approxi- mately 100 ft long with tapers on each end. At the time of construction, they cost roughly $10,000 per site. The sites do not include lighting. Two signs were installed for each site: one in advance of the site and one at the crash (accident) investigation site. The sign is blue with a white logo of a tow truck pulling a car. RAMP TURN RESTRICTIONS The Kansas Speedway in Kansas City, Kansas, hosts many popular racing events, in- cluding the NASCAR series. These races draw large crowds, resulting in much higher than usual demand on the nearby roadway network. To improve traffic operations for patrons and minimize the negative impacts to other users of the roadways, the Kansas DOT and the Kansas Highway Patrol implemented a comprehensive plan for directing traffic into and out of the speedway facility. This comprehensive traffic control plan involves both advance set-up and manual direction of traffic while patrons stream into the facility. The following are the major interchanges that are involved in this effort: • I-70 at K-7 • 110th and I-435 • I-435 and State Avenue • I-435 and Parallel Avenue Before race day, Kansas DOT staff erect 12 portable variable message boards and temporary signs at specific locations along the roadway, adjust permanent signs, and place traffic cones near where they will be needed. This advance work and the

139 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION subsequent teardown after the race day costs Kansas DOT approximately $10,000 in wages to Kansas DOT staff and the use of Kansas DOT equipment. Many races span the 2-day weekend, so an eight-person crew from Kansas DOT and a 16-person crew from the Kansas Highway Patrol are dispatched to manually direct traffic and manage the traffic control system. Ten cameras are located at various points along the route that provide staff with real-time information on the traffic patterns and help them make informed decisions. Kansas DOT spends approximately $10,000 on staff wages and equipment use during the two-day implementation of this system. The additional cost to the Kansas Highway Patrol for the 2-day deployment of this system is approximately $50,000 in officer wages and use of police vehicles and equipment. These costs are covered by the department’s own funds. Two other agencies are involved in the implementation of this plan: the Kansas City Police Department and the Bonner Springs Police Department. Each of these agencies sends officers to various locations within their jurisdiction to improve local traffic flow. The costs to these agencies are unknown; they are covered from each agency’s own funds. Altogether, there are an estimated 1,000 person-hours spent between all these departments for a single deployment of this system. The total cost to all departments combined is approximately $70,000. This cost must be paid each time the system is used, and it does not include the installation cost of the permanent infrastructure and design plans needed before the system was implemented. Five of the 10 cameras placed at various points along the roadways were installed as part of a project completed in 2010, which also included improvements to the five existing cameras. The total cost of this project was approximately $400,000. IMPROVEMENTS TO DETOUR ROUTES On August 1, 2007, the I-35W Mississippi River Bridge collapsed, displacing 154,000 daily vehicle trips. A study of the I-94/I-35W interchange revealed that 40% of these trips began or ended within the downtown area and 60% were pass-through trips. Three primary detour routes were identified for improvements: • TH-280 from I-35W to I-94, and I-94 from Hwy 280 to I-35W (Route 1) • I-694 from I-35W to I-94, and I-94 from I-694 to downtown (Route 2) • TH-100 from I-694 to I-394 (Route 3) The parenthetical letter designations that follow the descriptions of the projects listed in the following subsections are keyed to the locations marked in Figure 5.1. Route 1 TH-280 was converted from an expressway to a freeway to increase capacity. The projects along this corridor included the following: • The addition of a second lane to the ramp from TH-280 to I-35W/Hwy 36. This project cost $375,000 and was completed in August 2007. (A)

140 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION • The construction of a southbound one-way frontage road at Broadway Avenue to provide access to local business. This project cost $400,000 and was completed in August 2007. (H) • The construction of continuous lighting along TH-280. This project cost $200,000 and was completed in August 2007. (L) • The construction of a diamond interchange with two temporary signals at Hennepin–Larpenteur Avenue. This project cost $930,000 and was completed in August 2007. (J) • The construction of traffic management system infrastructure along TH-280 that included cameras, vehicle detectors, and dynamic message signs. This project cost $500,000 and was completed in August 2007. (D) • The elimination of access to TH-280 at each of two existing at-grade signals. This project cost $155,000 and was completed in August 2007. (M) I-94 was improved by constructing a fourth lane along I-94 in the eastbound and westbound directions. This project cost $1.2 million and was completed in August 2007. (G) Route 2 The following two projects were undertaken to improve operations along I-694: • The construction of a fourth lane on eastbound I-694 to TH-47. The interchange at TH47 was also modified to extend a through lane and provide a better lane drop condition. This project cost $170,000 and was completed in September 2007. (O) Figure 5.1. Map of individual project locations.

141 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION • The conversion of the shoulder of westbound I-694 to a bus-only lane. This proj- ect involved sign installation only. This project cost $10,000 and was completed in August 2007. (N) Although part of the detour Route 2, no improvement projects were undertaken for this section of I-94. Route 3 Travel lanes were added along TH-100 to increase capacity. The projects along this corridor included the following: • The addition of a second lane to the ramp from northbound TH-100 to eastbound I-694. The project also included lane widening along TH-100 to increase capacity, which was accomplished mostly through pavement marking changes. This project cost $17,000 and was completed in August 2007. (C) • The addition of an auxiliary lane along TH-100 from Duluth Street to TH-55. This lane addition was accomplished solely by changes to pavement markings. This project cost $30,000. (I) Other Improvements The following improvements were made near the immediate area of the collapsed bridge. Although not part of a formal detour route, these improvements provided opera tional benefits to traffic needing access to destinations near the site of the collapse: • The conversion of the existing one-lane entrance and exit ramps at the I-35W and 4th Avenue interchange to two-lane ramps. This project cost $112,000 and was completed in August 2007. (B) • The addition of cameras and vehicle detectors along Hwy 65. These improvements allowed signal operations personnel to monitor conditions and adjust signal tim- ings, which improved traffic flow and operations. This project cost $70,000 and was completed in August 2007. (E) • The addition of cameras and vehicle detectors along Hwy 47. These improvements allowed signal operations personnel to monitor conditions and adjust signal tim- ings, which improved traffic flow and operations. This project cost $70, 000 and was completed in August 2007. (F) • The addition of an eastbound right-turn lane on Washington Avenue for traffic entering the southbound I-35W on-ramp. The on-ramp was also widened, and new striping was installed on the improved ramp. This project cost $170,000. (K) • The addition of ramps at the I-35W and Hennepin Avenue interchange. This project had an estimated cost of $1,250,000 but was never completed. (P)

142 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION REDUCED CONSTRUCTION DURATION Several techniques for reducing construction duration are employed by the Texas DOT near Dallas, Texas: • Charging the contractor a “lane rental fee” for each hour that a traffic lane is shut down • Breaking a single project into multiple phases • Paying the contractor a bonus (per day) for finishing ahead of schedule • Charging the contractor a fine (per day) for finishing behind schedule These techniques vary in cost and are very sensitive to the traffic demand vol- umes of the roadway affected by the project. The contractor bonuses can range from $10,000 to $20,000 per day, with a maximum limit of $250,000. Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) is a soft- ware tool developed by the University of California Pavement Research Center through the UC Berkeley Institute of Transportation Studies and funded by the Federal High- way Administration (FHWA). This software helps agencies evaluate the cost of vari- ous construction scenarios for pavement rehabilitation projects, taking into account schedule, cost, and delay to traffic. FHWA obtained a group license from UC Berkeley for the software for use by all 50 state DOTs. The software has been used to justify accelerating construction schedules by showing how they can save the agency’s and the users’ money. One example is the I-15 Devore project in Iowa, which was completed in two 9-day periods, rather than the 10 months that would have been required if standard nighttime closures had been used. Traffic simulation models and the CA4PRS software showed that this accelerated schedule would save the agency $6 million and the road users $2 million. IMPROVED WORK SITE ACCESS AND CIRCULATION The Washington State Department of Transportation Design Manual, Chapter 10, Work Zone Safety and Mobility (Washington State Department of Transportation 2009) contains various techniques and strategies to minimize the effect of a work zone on traffic operations and traffic safety. Because state DOT policy prohibits hauling ingress and egress from a live traffic lane on high-speed or high-volume roadways, alternate methods of delivering materials are required. Examples of techniques that have been employed on Washington State DOT projects include the following: • Material stockpiling on site. This technique involves contractors planning ahead and creating stockpile sites within the work zone area. The materials are delivered during low-demand time periods and used when they are needed. • Material processing on site. The contractor strategically positions portable con- crete or asphalt plants on site to minimize access conflicts.

143 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION • Dedicated truck deceleration and acceleration lanes. This technique involves the construction of an additional temporary lane within the work zone space to allow delivery trucks to decelerate when entering and accelerate when exiting. Barrier separation of these lanes from normal travel lanes is preferred. In most cases, it may be difficult to find available space within the work zone, but when possible, this method works well. • Temporary access granted from other property owners. This technique involves the contractor seeking cooperation from adjacent property owners, local agencies, and FHWA to allow access for delivery trucks via nearby nonfreeway roads. • Alternate private or local access. Through easements and local agency permits, contractors may obtain alternate access. • Total closure. This should be done during periods of low demand. By temporarily closing the entire roadway, work can be completed quickly. This technique is par- ticularly useful in conjunction with weekend work. • Lane closure for hauling access. This technique should be used only during peri- ods of low traffic demand to avoid significant congestion. This technique would be recommended in conjunction with night work, for example. • Lane closure using QuickChange movable barrier. This allows a traffic lane to be closed for periods of low demand and then easily reopened during periods of high demand. • Closure of ramp to allow “wrong-way” material hauling. This technique involves the full or partial closure of a downstream off-ramp. Trucks delivering materials to the project site travel in the closed lane in the opposite direction of normal traffic. • Project staging. This technique involves advance planning of a series of project phases, such that materials for later stages can be delivered and stockpiled before ramps or lanes are opened. • Use of conveyer system. Materials can be delivered to an area near the work site with low traffic volumes and brought to the location where they are needed through an on-site conveyer system. • Hauling allowed only during specified conditions. This technique involves a per- formance specification to the contractor that only allows materials to be delivered when certain conditions are met. For example, material delivery would only be allowed if vehicle demand volumes were below a certain threshold. • Rolling slowdown operations. These may be used to provide gaps in the normal traffic stream to allow trucks to deliver material to the site. This is intended to reduce the occurrence of sudden speed reductions and the potential for rear-end collisions. • HOV lane use. HOV-only lanes may be used by trucks delivering materials to the site.

144 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION ANIMAL–VEHICLE COLLISION DESIGN CONSIDERATIONS Five wildlife crossings were constructed along US-93, a two-lane highway near Wells, Nevada, by the Nevada DOT between 2000 and 2010. This section of roadway is along a migratory path of mule deer. It is estimated that 3,500 deer use one of the five crossings each fall and again each spring. These crossings were built over a series of three projects. The first project was an overcrossing built over an existing cut section of the roadway. The road profile remained as it was, so only a small amount of earthwork was required. The overcross- ing was 185 ft long and 55 ft wide. The total cost to the Nevada DOT was $1.8 million, and another agency paid the $300,000 cost of installing fencing around the crossing. The next project consisted of the construction of three undercrossings under US-93 that were constructed one-half at a time to allow traffic to continue to flow during con- struction. The undercrossings consisted of a 28-ft-wide by 16-ft-tall metal culvert. The total cost for these three undercrossings was $2.2 million. The third project was the construction of an overcrossing 100 ft long by 55 ft wide. A significant amount of earthwork was required for this crossing, and the road- way was lowered 14 ft from its original profile. An 8-ft woven wire fence was installed with this crossing, and is included in the total $3.15 million cost of this project. These five crossings are all along a single 12-mi section of US-93 that experi- enced an estimated 70 to 80 wild animal–vehicle crashes per year before these projects began. These crossings have resulted in an 80% to 90% reduction in wild animal– vehicle crashes along this roadway. CONTRAFLOW LANES: EVACUATION The Texas DOT has identified I-10 West as a potential hurricane evacuation route for the City of Houston. In several places along this route, water-filled traffic barriers have been used to separate directions of travel. In an emergency evacuation, the water can be drained from these barriers, allowing them to be moved to allow contraflow of the eastbound lanes of I-10 during the evacuation. In addition, the outside shoulder of I-10 may be used as a travel lane during evacuations. This may be done with or without the use of contraflow lanes. For other evacuation routes, the inside shoulder may be designated as the “evaculane” and marked with a hurricane evacuation symbol. Resi- dents know when they are permitted to use the lane through local media reports and signs along the route. During times when the shoulder serves as an evaculane, minor accidents and disabled vehicles must be moved off the shoulder or to the nearest ramp. The entire I-10 evacuation route from Houston to San Antonio covers nearly 200 mi of freeway. Costs for using the water-filled barriers along the route were approx- imately $250,000. However, the most significant cost associated with this treatment is personnel time during each evacuation event. At each interchange, it is recommended that three workers direct traffic onto the freeway. Law enforcement personnel are pre- ferred for this role, and it is also recommended that each person directing traffic have a vehicle to bring attention to themselves and for their protection. Many interchanges

145 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION are involved in the Houston evacuation route, so dispatching all necessary personnel can be an expensive undertaking. Texas DOT has posted several videos illustrating and explaining the use of emer- gency evacuation routes. They provide guidance to drivers on what to expect during an evacuation and show renderings of the temporary traffic control to guide drivers onto the contraflow section, as well as the signs they should expect to encounter. Con- traflow guide signs are typically folded signs that are opened during an evacuation. Evacuation plans have also been developed for Corpus Christi, Texas. The main evacuation route is I-37 toward San Antonio, although the DOT states that this route would not be able to accommodate all coastal traffic and that other routes should be considered depending on the predicted path of the storm. The I-37 evacuation plan has three stages. In the first stage, shoulders are opened for use. In the second stage, contra flow is deployed between the urban areas, and in the third, contraflow begins in the urban center of Corpus Christi and includes several interchanges where traffic control will be modified to accommodate contraflow. HOV LANES AND TOLL LANES Several freeways in Houston, Texas, have reversible HOV lanes between opposing directions of travel. These lanes are available to inbound HOV traffic in a.m. peak periods and outbound HOV traffic in p.m. peak periods. I-45 near Sam Houston Toll- way is one such road. The HOV lane is separated from the general travel lanes by concrete barriers and may only be entered or exited at specific access points along the freeway. Barriers are moved at each end of the reversible HOV lane during off-peak periods to switch the direction of travel. When major incidents take place that block freeway lanes and cause significant congestion, the HOV lanes are temporarily opened to all traffic. This occurs approxi- mately four times per year. The traveling public is made aware of the lane opening by dynamic message signs and via television and radio news announcements. The Texas DOT Traffic Management Center makes the decision to open the lane and relays the message through news station personnel. Thus, there is little, if any, cost to implement this treatment. Opening the HOV lane to all traffic is done relatively rarely because of the nega- tive impact it has on HOV vehicles. Texas DOT prefers to give an advantage to HOV drivers, so that they have better travel conditions than the general traffic, in order to encourage carpooling and bussing. Temporarily opening the HOV lane to all traffic eliminates this incentive. On very rare occasions, the DOT waives toll fees on certain toll-only facilities in the Houston area in response to major incidents. The cost of doing this is the lost revenue that would have been collected at the toll booths. The public is apprised of the temporarily waived tolls via television and radio in the same way as the HOV lane opening.

146 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION WORK ZONE EXPRESS LANES Work zone express lanes were used during a construction project in downtown Tucson, Arizona, along the I-10 corridor from 2007 through 2009. The existing freeway im- provements included lane additions and the reconstruction of seven bridges and under- passes along a 4.5-mi segment as part of a $200 million project. Before construction, express lanes were built along the entire length of the work zone for traffic desiring to bypass local traffic. A mobile intelligent transportation system center was established with approximately 72 cameras to monitor the entire project area comprehensively. Because shoulders were not provided along the express lanes, existing ramps (not in use by through traffic) were designated as emergency pullouts, and tow trucks were available at all times to assist in clearing any incidents. In addition, parallel arterial roads were upgraded to provide additional through lanes, and the traffic signals along the route were retimed to adjust to the new traffic demands. RAMP METERING Minnesota Approximately 430 ramp meters were in operation in 2006 during the morning and evening peak periods in the Minneapolis–St. Paul metropolitan area. Some of the installations were pretimed, and others were traffic responsive and part of a larger networkwide metering system. This metropolitan area has the most comprehen- sive metering system in the nation. In 2000, the Minnesota DOT conducted a state legislature– mandated study of the metering program. Key results from this study are included in the Chapter 3 discussion of this treatment. Washington Seattle has had approximately 120 ramp meters in place since 2002. They are all part of a traffic-responsive systemwide initiative. The meters operate during the morning and afternoon peak periods, as well as during incidents and special events. The system is designed to be able to respond to special nonrecurrent congestion needs. California The California DOT (Caltrans) has over 1,000 ramp meters in place throughout the state, including installations in major metropolitan areas such as Los Angeles and San Diego. The installations include a variety of approaches, from local pretimed installa- tions to large networkwide traffic-responsive systems. Caltrans has even developed a ramp metering design manual for the state. FOG DETECTION California Caltrans District 10 experiences seasonal fog and dust-related visibility problems that have caused numerous multivehicle crashes. In 1990, Caltrans proposed a multi- sensor automated warning system based on the expansion of SR-120 connecting I-5

147 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION and SR-99. The system includes 36 traffic speed monitoring sites, nine complete re- port meteorological stations, and nine changeable message signs for warning drivers. This system is referred to as the Caltrans Automated Warning System (CAWS). CAWS detects reduced visibility conditions and traffic congestion. When sensors determine visibility is below 500 ft, changeable message signs display “FOGGY CONDITIONS AHEAD”; when visibility is below 200 ft, the signs display “DENSE FOG AHEAD.” The traffic monitoring system sensors collect traffic count and speed information. When speeds are below 35 mph, the changeable message signs display “SLOW TRAFFIC AHEAD” warnings, and when speeds are below 11 mph, the signs display “STOPPED TRAFFIC AHEAD” warnings. The weather-related instruments of CAWS also measure wind speed. When wind speeds register above 25 mph, the changeable message signs display “HIGH WIND WARNING.” These messages are intended to reduce crashes caused by low visibility due to dust. The cost of the San Joaquin Valley system that was implemented in the early 1990s was estimated at approximately $3.6 million ($1.32 million for Caltrans and $2.35 million for the California Highway Patrol). Tennessee In Tennessee, two major fog-related crashes triggered the installation of a fog detection system in 1993, on the Hiwassee Bridge on I-75. The system includes the following: • Road weather information systems • Fog detectors • Speed detectors • Variable message signs • Changeable speed limit signs • Swing gates • Fixed signs with flashers • Highway advisory radio systems If speeds fall below 45 mph or if visibility falls below 1,320 ft, an alert is sent to dispatch a highway patrol officer to assess the situation. An automatic message is sent to the variable message sign notifying drivers of potential fog ahead. If the high- way patrol officer confirms the presence of fog, the variable message changes from “POTENTIAL FOG AHEAD” to “FOG AHEAD.” Variable speed limit signs are also activated, as follows: • When visibility is between 480 and 1,320 ft, the speed limit is set to 50 mph. • When visibility is between 241 and 480 ft, the speed limit is set to 35 mph. • When visibility is below 240 ft, the road is closed and traffic is detoured onto a nearby U.S. highway.

148 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION From December 1993 to January 1995, there were 77 activations for fog. All activations required lowering the speed limit to 50 mph; 10 of the activations required a further lowering of the speed to 35 mph. Two road closures took place: one due to fog, the other due to a nearby chemical plant explosion of toxic smoke. The system is monitored by the highway patrol but was installed and maintained by officials from the Tennessee DOT. This system was installed for a total cost of approximately $4.5 million. FLOOD WARNING SYSTEM Dallas, Texas The City of Dallas, Texas, implemented a flood warning system in April 2000. The system is made up of three components: • A central computer system • One sensor at each site • One to six changeable message signs at each site The sensor monitors the elevation of a nearby stream and reports every 20 min to the central computer. When the flood water reaches the edge of the roadway, a float switch tells the sensor to signal the sign to change to the warning text and turn on the flashing lights. The sign sends a message back to the sensor confirming that everything is working properly. The sensor radios this information back to the central computer. Pages are sent to staff, and messages are printed out at the appropriate street services district alerting them of the need to place barricades at the location as soon as possible. The signs and sensors are battery powered and recharged with solar cells. All com- munication between the sensors and signs and the sensors and the central computer are by radio. The sensors normally control the signs without intervention from the central computer. However, the central computer can issue commands to turn on the signs and lights. The signs include changeable text messages and red flashing lights. In the nonalarm state, the lights are off and the sign shows “HIGH WATER WHEN FLASHING.” In the alarm state, the lights alternate flashing and the sign changes to “DO NOT ENTER HIGH WATER.” The signs and lights are equipped with sensors to detect the status. Fort Worth, Texas The City of Fort Worth, Texas, has a system consisting of both manual and automatic barrier gates, as well as flashing beacons that warn motorists of flooded roadways. The system, which the city installed in 2003, includes 43 advance warning signs at 18 sites. Houston, Texas The City of Houston, Texas, has over 185 sites with 550 sensors that include 12 low- water crossing areas.

149 DESIGN GUIDE FOR ADDRESSING NONRECURRENT CONGESTION WIND WARNING SYSTEM Oregon A wind warning system used on the Yaquina Bay Bridge in Oregon includes an an- emometer to measure wind speed, which automatically activates flashing beacons on two static signs when wind speeds reach a preset level. This system was constructed for approximately $20,000. Montana A wind warning system is used along I-90 in the Bozeman–Livingston area in Montana. The following messages are displayed to motorists: • If wind speeds are between 20 and 39 mph: CAUTION: WATCH FOR SEVERE CROSSWINDS • If wind speeds are over 39 mph: SEVERE CROSSWINDS: HIGH PROFILE UNITS EXIT Nevada A wind warning system is used along US-395 in Washoe Valley, between Carson City and Reno, Nevada. The following messages are displayed to motorists: • If wind speeds are between 15 and 30 mph and maximum wind gusts are 20 to 40 mph: CAMPERS AND TRAILERS NOT ADVISED • If wind speeds are greater than 30 mph and maximum wind gusts greater than 40 mph: CAMPERS AND TRAILERS PROHIBITED New York A wind warning system is used on the Ogdensburg–Prescott International Bridge in New York. The following messages are displayed to motorists: • If wind speeds are between 30 and 40 mph: HIGH WIND ADVISORY. USE CAUTION ON BRIDGE. (No vehicle restrictions.) • If wind speeds are between 40 and 50 mph: HIGH WINDS. REDUCE SPEED ON BRIDGE. (Restrictions: escorted vehicles are individually assessed on their load.) • If wind speeds are greater than 50 mph: HIGH WINDS. REDUCE SPEED TO 5 mph. (Restrictions: intermittent restrictions of recreational vehicles [motor homes and travel trailers], motorcycles, and empty container trucks, as warranted by bridge manager or designee.) • If wind speeds are greater than 75 mph: BRIDGE CLOSED. (All traffic restricted.)