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Planning for Truck Routes and Other Related Considerations 9 mobility, access, and circulation. Design considerations include lane width, turning radii, median island radii, vertical clearance, and location of fixed objects (e.g., signs, utility and signal poles, street trees, other roadside features) (City of Portland 2008). Industrial areas may not experience as many pedestrians, bicyclists, or transit users as urban areas; however, even industrial road- ways need to safely accommodate and balance the needs of pedestrians, bicyclists, and transit. Each roadwayâs user mix and resulting needs should be assessed on a case-by-case basis. â¢ Urban Core AreasâRoadways within urban cores and other diverse activity areas typically experience a mix of user modes, including motor vehicles and trucks, pedestrians, bicyclists, and transit users. Designing to accommodate trucks should not conflict with the needs of motor vehicles, pedestrians, bicyclists, and transit users in urban areas. Achieving an appro- priate balance of the various user modes in design will require careful consideration of the specific mix of user modes for a particular site. In other words, it may be important to accom- modate freight on one urban corridor but focus on pedestrian needs on a nearby corridor. Designers need to âapply sound design principles within different urban environments to address a variety of multimodal transportation needsâ (City of Portland 2008). When designating a truck route that is not already an arterial, it is important that such routes not split neighborhoods in urban areas. â¢ Residential AreasâResidential areas and other community-oriented areas typically experience low volumes of truck traffic and are primarily designed for automobile, pedestrian, and bicycle movements. With the exception of fire trucks, garbage trucks, and the occasional moving truck, most trucks entering residential areas are smaller-sized delivery trucks (e.g., FedEx, UPS). Some agencies allow designated truck routes through residential areas where needed for continuity of the truck route network, but the density of such residential areas is often limited. 3.1.2 Roadway Functional Classification Land use should be considered in conjunction with roadway functional classification in estab- lishing truck routes. Arterials often serve as truck routes through land uses of all types, although arterials with residential development are less desirable as truck routes than arterials through other land-use types. Collectors are most suitable as truck routes when they serve commercial or industrial development. Local roads and streets are seldom suitable as truck routes, except when they serve a specific facility for which there is no alternative truck route. 3.1.3 Identification of Strategic Freight Corridors A number of transportation agencies have directed their statewide planning process toward establishing strategic freight corridors to recognize the routes that are used most extensively for truck movements. The strategic corridors provide a focus for review of geometrics to accommo- date trucks; review of congestion levels; review of regional freight flows; review of access connec- tions to freight centers, including services, terminals, and high-volume shippers/receivers; and prioritization of roadway improvements. Where freight advisory committees have been estab- lished, the committee also has a key role in identifying the strategic corridors. As with the National Highway Freight Network (see Section 3.2.4) established at the federal level, state strategic freight corridors have no legal or regulatory status, but simply provide a management tool for prioritization and decisionmaking. 3.1.4 Interagency Collaboration Collaboration between various stakeholders, including transportation agencies, trucking companies/associations, residents, property owners, and developers, during the planning process is likely to result in a better design for trucks as well as other roadway users. Several transportation
10 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide agencies have established statewide or local freight advisory groups that meet regularly (e.g., bi-monthly, quarterly) to discuss safety, operational, and design issues for accommodating trucks on the roadway system. The collaborative approach may help to align access issues with context classification and improve site plans in terms of freight loading zones and alternative access locations. Wherever a new development is proposed that would generate high truck volumes, traffic impact studies should be reviewed to consider the effects of the proposed development on the roadway system. Coordinated discussion with the trucking industry is encouraged to make sure the following design issues are considered: â¢ Turning radii. â¢ Intersection dimensions. â¢ Storage length. â¢ Driveway dimensions. â¢ Parking. 3.1.5 Truck Delivery Considerations In recent years, the demand for truck deliveries has increased substantially with the increased popularity of e-commerce. To minimize the impact of truck deliveries on motor vehicle traffic, pedestrians, and bicyclists, and to reduce traffic delays and the potential for crashes, many trucking companies and businesses have strategized new approaches to managing deliveries, including making deliveries during off-peak or nighttime hours. Challenges associated with this type of operation may include (1) the possible need for receivers of these deliveries to staff up during what are often nonbusiness hours, (2) availability of parking needed for staging of trucks just outside the city, so that trucks can wait for the time during which deliveries are allowed, and (3) possible increased costs for truck operators and/or shipment receivers due to added staff and equipment waiting time prior to deliveries. An important consideration in the planning of bicycle lanes is the location of frequent truck deliveries. If possible, placing a bicycle lane on a route where frequent truck deliveries occur should be avoided because the presence of parked trucks in a bicycle lane would be problematic for bicyclists. In some cases, for example, if a one-way street is involved, placing the bicycle lane on the other side of the street from frequent delivery locations may be preferable. 3.1.6 Site Layout and Internal Circulation Trucks require more space to maneuver and have different operational characteristics than cars, with additional needs related to roadway geometry. Trucks also involve different supporting facilities for which access and location are of primary importance. In addition, interactions between trucks and multimodal users must be considered, particularly in high-volume usage areas. This section identifies site layout needs to adequately provide for site circulation where a significant number of trucks are anticipated. The location of gates providing access to the site should be considered as part of the site layout, as discussed in Section 4.5.11. Special Characteristics of Trucks Trucks have specific site layout needs, especially at locations expected to accommodate a substantial volume of trucks. Trucks have greater turning radii than other vehicles and require more space for turning maneuvers. Wider lanes and a greater corner radius may be necessary to accommodate larger tractor trailers and other wide-bodied vehicles. Auxiliary lanes or addi- tional storage length for these lanes may be necessary to safely facilitate turns on and off the
Planning for Truck Routes and Other Related Considerations 11 property. In addition, storage areas to allow trucks to queue without obstructing through traffic or other roadway users may be needed. Interactions between trucks and other roadway users should be organized to minimize traffic conflicts where possible. The selection of a design vehicle as well as a design speed will play a major role in site layout. Consideration of Site Type There are different types of sites that illustrate the varying conditions in which trucks need to be accommodated. This section examines three distinct settingsâa shopping center, an industrial or freight-oriented area, and an urban core or diverse activity areaâas examples of different site characteristics and how they impact truck operations and usage. Each site is designed with different goals and development patterns that have implications for street design and roadway engineering. However, the site layout must support the various types of traffic that will be needed to serve the site so that it can function effectively and efficiently. Shopping areas, as illustrated in Figure 1, are examples of sites where trucks and other vehicles require access and have different needs. Trucks require access to the loading docks, shipping bays, and delivery facilities to complete their trips. This differs from private vehicles, which require general parking and pedestrian access to entries and sidewalks. The site circulation facilities for trucks should be planned separately from, yet concurrently with, facilities for other vehicles. Access from the street to the shopping center may be from different entrances. Whereas most a. Aerial view of suburban shopping area. (Photo source: Google Earth.) b. Non-standard sign used at shopping center to guide truck drivers to loading docks and customers to parking areas. (Photo source: AECOM.) Figure 1. Shopping areas.
12 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide shopping centersâ frontages face the street for easy access to shoppers, delivery trucks mainly access the backs of stores for deliveries. The separate access facilities for trucks should avoid pedestrian and vehicle conflicts. For trucks, getting to the site is as important as staying there; an easy access route leading to an adequate space for short- and long-term loading and unloading of goods is desirable. This dedicated space is more than a parking space; it needs to have sufficient clearance for the quick loading and turning around of trucks. This should be a restricted area to ensure safety of users and efficiency of the delivery. Egress from the delivery area should be as protected as ingress. Lanes to be used by trucks should be wider than travel lanes used predominantly by cars. Industrial areas, or freight-oriented areas, as illustrated in Figure 2, exemplify sites where trucks are not as likely to interact with other users, but still require site planning for efficient and safe usage by trucks. Industrial parks tend to be located in wide, expansive areas, so narrow access roads that may be located in an urban core are not generally an issue. The access roads from other main thoroughfares and highways need to provide direct access to the industrial park without circuitous routing. It is thus advantageous for the industrial park to be located adjacent to the highway, such as on a dedicated truck exit that has restricted entry. With a dedicated access road, it could be specifically tailored for heavy truck traffic. This could include greater turning radii and geometry, such as wider lanes and asphalt engineered for heavy loads. One of the most challenging settings for truck site planning is a dense urban environment, often referred to as an urban core, as illustrated in Figure 3. In downtown development areas, pedes- trian usage and walkability are often prioritized. Passenger cars face spatial challenges in the urban a. Aerial view of industrial area. (Photo source: Google Earth.) b. Truck activity near access to industrial area. (Photo source: AECOM.) Figure 2. Industrial areas.
Planning for Truck Routes and Other Related Considerations 13 environment, but such challenges are even more significant for trucks. These include parking maneuvers, loading, circulation, capacity, and queuing. Truck circulation in these areas should be planned concurrently with the rest of the site plan to ensure that trucks are properly integrated to reduce impacts on the area and effectively serve the area. Route or time-of-day restrictions may be options to minimize potential conflicts (Anderson 2017; Holguin-Veras et al. 2015). 3.2 Truck Routing Truck routes, as defined in this Guide, include roads formally designated as truck routes as well as any road that carries a substantial volume of trucks. Truck routes should be designed to accom- modate the types of trucks that use the route with considerable frequency. The formal designation a. Aerial view of urban core area. (Photo source: Google Earth.) b. Truck turning across pedestrian crossing. (Photo source: AECOM.) Figure 3. Urban core areas.
14 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide of truck routes is a key operational and planning activity that should consider the truck demand volumes, the origins and destinations of truck shipments, and the suitability of particular roads and corridors to accommodate trucks of specific sizes. When designating a truck route that is not already an arterial, it is also important that such routes not split neighborhoods in urban areas. 3.2.1 National Network Establishment of a National Network (NN) of truck routes was mandated in the 1982 Surface Transportation Assistance Act (STAA). The NN includes the entire Interstate Highway System (with minor exceptions) and other roads designated by the U.S. Secretary of Transportation based on recommendations by the states. The NN includes approximately 200,000 mi of roads and has been very stable in extent of 25 years. Changes in the NN may occur when a state petitions the Secretary of Transportation to add or delete roads from the NN. The NN was designated by the U.S. Secretary of Transportation based on the following criteria (23 CFR 658.9): â¢ For those states with detailed lists of individual routes, the routes on the NN have been designated on the basis of the following criteria: â The route is a geometrically typical component of the Federal-Aid Primary1 (FAP) system, serving to link principal cities and densely developed portions of the states. â The route is a high-volume route utilized extensively by large vehicles for Interstate commerce. â The route does not have any restrictions precluding use of conventional combination vehicles. â The route has adequate geometrics to support safe operations, considering sight distance, severity and length of grades, pavement width, horizontal curvature, shoulder width, bridge clearances and load limits, traffic volumes and vehicle mix, and intersection geometry. â The route consists of lanes designed to be 12 ft or more in width or is otherwise consistent with highway safety. â The route does not have any unusual characteristics causing current or anticipated safety problems. â¢ For those states where state law provides that STAA authorized vehicles use all or most of the FAP system, the NN is no more restrictive than such law. 3.2.2 Truck Size and Weight on the National Network Federal regulations for the NN concerning the length of conventional tractor-trailer trucks require that (23 CFR 658.13) â¢ No state shall impose a length limitation of less than 48 ft on a semitrailer operating in a tractor-semitrailer combination. [Note: In 25 states, trucks with 53-ft semitrailers are permitted to operate on the NN under grandfather provisions; in three additional states, trucks with 53-ft semitrailers and specific limitations on kingpin-to-rear-axle (KPRA) distance are permitted to operate on the NN under grandfather provisions.] â¢ No state shall impose a length limitation of less than 28 ft on a semitrailer or trailer operating in a tractor-semitrailer-trailer combination. â¢ No state shall impose an overall length limitation on commercial vehicles operating in tractor- semitrailer or tractor-semitrailer-trailer combinations. 1 Since the establishment of the NN, the FAP system has been discontinued and replaced by the National Highway System (NHS)âsee Section 3.2.5.
Planning for Truck Routes and Other Related Considerations 15 â¢ No state shall prohibit tractor-semitrailer-trailer combinations. â¢ No state shall prohibit the operation of semitrailers or trailers that are 28.5 ft long when operating in a tractor-semitrailer-trailer combination if such trailer or semitrailer was in actual and lawful operation on December 1, 1982, and such combination had an overall length not exceeding 65 ft. â¢ No state shall prohibit the use of trailers or semitrailers that were in actual or lawful use in such state on December 1, 1982. â¢ If, on December 1, 1982, state length limitations on a semitrailer were described in terms of the distance from the kingpin to rearmost axle, or end of semitrailer, the operation of any semitrailer that complies with that limitation must be allowed. Federal regulations for the NN concerning the length of conventional tractor-trailer trucks are as follows (23 CFR 658.15): â¢ No state, with the exception of Hawaii, shall impose a width limitation of more or less than 102 in. on vehicles operating on the NN. These length and width limits presented do not include the following (23 CFR 658.16): â¢ Rearview mirrors, turn signal lamps, handholds for cab entry/egress, splash and spray suppres- sant devices, and load-induced tire bulge. â¢ All non-property-carrying devices or components thereof: â At the front of the semitrailer or trailer. â That do not extend more than 3 in. beyond each side or the rear of the vehicle. â That do not extend more than 24 in. beyond the rear of the vehicle and are needed for loading and unloading. â Are listed explicitly in Appendix D to 23 CFR 658. Federal regulations for the Interstate Highway System concerning the weight of conventional tractor-trailer trucks require, except for certain grandfathered vehicle weight limits or where an overweight permit is issued, the following (23 CFR 658.17): â¢ The maximum gross vehicle weight shall be 80,000 lb except where a lower gross vehicle weight is dictated by the bridge formula (see below). â¢ The maximum gross weight upon any one axle, including any one axle of an axle group, is 20,000 lb. â¢ The maximum gross weight on tandem axles is 34,000 lb. â¢ The gross weight on two or more consecutive axles exceeds the following bridge formula, except that two consecutive sets of tandem axles may carry a gross load of 34,000 lb each if the overall distance between the first and last axle is 36 ft or more and the total gross weight of the vehicle does not exceed 80,000 lb. W LN N N 1 12 36 (1)( )= â + + where: W = maximum weight carried on any group of two or more axles (lb). L = distance between the outer axles in any group of two or more axles (ft). N = number of axles in the axle group. â¢ States may not limit tire loads to less than 500 lb per inch of tire or tread width, except that such limits may not be applied to tires on the steering axle. â¢ States may not limit steering axle weights to less than 20,000 lb or the axle rating established by the manufacturer, whichever is lower.
16 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide 3.2.3 Access Routes to the National Network Federal regulations indicate that states (or local jurisdictions) may not enact or enforce any law denying reasonable access to vehicles with dimensions authorized by the STAA between the NN and terminals; and facilities for food, fuel, repairs, and rest; or denying reasonable access to points for loading and unloading. States may not enact or enforce any law denying access within 1 road-mile from the NN along the most reasonable and practicable route available except for specific safety reasons on individual routes. Distinctions between vehicle types shall be based only on significant, substantial differences in their operating characteristics. Blanket restric- tions on 102-in.-wide vehicles shall not be imposed. Vehicle dimension limits shall not be more restrictive than federal requirements. Truck operators may request access from the NN by spe- cific truck types along specific routes to points of loading and unloading, and states shall have procedures for review of such access routes within 90 days. 3.2.4 National Highway Freight Network The Fixing Americaâs Surface Transportation (FAST) Act of 2015 mandated creation of a National Highway Freight Network (NHFN) to strategically direct federal resources toward improved performance of the highway portions of the U.S. freight transportation system. The NHFN is primarily a device for prioritizing federal funding; there are no truck size and weight regulations applicable specifically to the NHFN. The NHFN consists of four components: â¢ Primary Highway Freight System (PHFS)âconsisting of most of the Interstate Highway System and a few additional roads. â¢ Other Interstate Highways not on the PHFS. â¢ Critical Rural Freight Corridors (CRFCs). â¢ Critical Urban Freight Corridors (CUFCs). The NHFN is a subset (including about 25%) of the NN, not including the CRFCs and CUFCs, which have not been completely selected yet. 3.2.5 National Highway System The NHS includes the Interstate Highway System as well as other roads important to the U.S. economy, defense, and mobility. NHS roads receive special consideration in planning and funding road improvements because the design of improvement projects on NHS roads involve a greater level of federal agency review than on other roads. The NHS differs from the NN in that the NHS includes roads of importance to all travel modes, not just trucks. Both the NHS and the NN include approximately 200,000 mi of road, and there is substantial overlap between the two systems. However, the NN includes approximately 65,000 mi of roads not on the NHS, and the NHS includes approximately 50,000 mi of road not on the NN. The subsystems of the NHS include the following: â¢ Interstate highways. â¢ Other principal arterials. â¢ Strategic Highway Network (STRAHNET). â¢ Major strategic highway network connectors. â¢ Intermodal connectors. Many Interstate highways and other principal arterials are important truck routes. STRAHNET highways are a network of roads that has been designated as important to U.S. stra- tegic defense, including transportation to and from defense facilities, continuity, and emergency capabilities for defense purposes. Major strategic highway network connectors provide access
Planning for Truck Routes and Other Related Considerations 17 routes between STRAHNET roads and major military installations. Intermodal connectors pro- vide access between NHS roads and major intermodal facilities, such as airports, ports, and rail yards. STRAHNET roads, major strategic highway connectors, and intermodal connectors are typically designed to accommodate large trucks and carry substantial volumes of truck traffic. 3.2.6 Truck Route Designation by Individual State and Local Agencies State and local agencies are free to designate truck routes or to prohibit all trucks, or trucks of particular sizes or weights, from using roads that are not part of the NN. Such designations and prohibitions can generally be made without reference to federal regulations or criteria. However, if a particular road is requested as part of an access route to the NN, any decision to deny that request must be based on rational, safety-related criteria. Specific considerations in identifying and designating truck routes are discussed in Section 3.2.7. Individual agencies communicate truck route designations and prohibitions to the trucking industry in a variety of manners. For example, California focuses on mapping approved service access and terminal access to the NN and signing of service access and terminal routes that truck drivers can follow. Michigan publishes maps for truckers showing âgold routes,â which constitute the NN, and âgreen routes,â which are other routes where large trucks can operate without restriction. The gold and green routes together constitute most of the state highway system. (Note: in the printed version, the gold routes are light gray and the green routes are darker gray. The electronic versionâposted on the web at www.trb.orgâretains the color version.) The maps also iden- tify a limited number of state highways where trucks are prohibited, or truck size or weight is restricted. A sample of Michiganâs truck route map is shown in Figure 4. Figure 4. Sample of Michigan truck route map (Source: Michigan DOT).
18 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide Colorado publishes maps showing designated routes that must be used by trucks hauling nuclear or other hazardous materials. Trucks loaded with hazardous materials subject to the Colorado routing regulations must use the designated routes. For local pickups and deliveries, hazardous materials trucks must avoid populated and residential areas, if possible, while utilizing the shortest and most direct route to minimize distance traveled off the designated route system. The Federal Motor Carrier Safety Administration (FMCSA) maintains a website known as the National Hazardous Materials Route Registry (www.fmcsa.dot.gov/regulations/hazardous- materials/national-hazardous-materials-route-registry-state/) that identifies all roads in the United States that are designated for travel by trucks carrying hazardous materials. It also identifies roads on which trucks carrying hazardous materials are restricted or prohibited. 3.2.7 Factors to Consider in Identifying and Designating Truck Routes The following factors should be considered in identifying and designating truck routes: â¢ Truck characteristics â Design vehicle dimensions and turning performance â Existing and anticipated usage by OSOW vehicles â¢ Roadway network characteristics â Functional classification â Position of roadway in transportation network and connectivity needs â Network constraints â Available alternative routes â¢ Roadway facility characteristics (including access management provisions) â Lane width â Shoulder width â Traffic-signal spacing â Driveway density and design â Median treatment and related features â Auxiliary lanes â Presence of bicycle facility â Height restrictions â Weight restrictions â¢ Land-use and environmental characteristics â Land use immediately adjacent to the roadway and in nearby areas â Location relative to land uses that generate truck movements â Location relative to environmentally sensitive areas â¢ Operational and safety characteristics â Traffic volume and congestion levels â Existing truck volume â Existing percentage of trucks in traffic stream â Pedestrian volumes â Bicycle volumes â Traffic speed â Split between through traffic versus local traffic Among these parameters are considerations associated with roadway access management strategies, including the following: â¢ Median treatment and related features, such as installation of medians to reduce head-on conflicts and selection of median width to accommodate U-turns.
Planning for Truck Routes and Other Related Considerations 19 â¢ Traffic-signal spacing that allows for progression commensurate with the posted speed. â¢ Design and operation of driveways, such as design of driveway width and profile to accom- modate trucks as well as other users and provision of corner clearance near intersections. â¢ Conventional intersection designs, such as construction of auxiliary lanes and needed turning geometry. â¢ Alternative intersection designs, such as provisions for indirect left turns and construction of roundabouts. Although truck routes, whether formally designated or not, may represent most of the mile- age that a truck needs to travel between its trip origin and destination, consideration must also be given to the âfirst mileâ and the âlast mileâ in truck route planning. The first mile is the connection needed to get from the trip origin to the truck network; while the last mile is the connection needed to get from the truck network to the trip destination. Routing options for these connections may require special consideration, because the roadways involved are often not part of any truck network, may not be frequently used by trucks, and may be located in built-up areas. As a result, these connections may represent significant challenges to finding a route that can accommodate the truck movement without adversely affecting the roadway facility, while being sensitive to the needs of adjacent communities. In truck route planning, agencies and truck operators need to recognize that achieving this balance may require further investigation to select the route to use. Access management provisions along the routing options (e.g., signal spacing, median cross section, auxiliary lanes) should be considerations in the route selection. (See Section 3.2.1 for information on the NN and Section 3.2.3 for information concerning federal regulations that pertain to access routes to the NN.) 3.2.8 Truck Prohibitions State and local transportation agencies have the authority to prohibit all trucks, or trucks that exceed particular size or weight limits, on roads where this makes engineering sense, except for roads on the NN. However, truck prohibitions or restrictions are only practical where there are suitable alternative routes for trucks. Federal law in 49 USC 5112 allows states, local jurisdic- tions, and Indian tribes to designate routes for or prohibit transportation of hazardous materials shipments requiring placarding on particular routes, but such decisions must enhance public safety and cannot be made arbitrarily. Routing regulations for hazardous materials trucks must be made in consideration with other affected jurisdictions and must maintain reason- able routes for hazardous materials trucks to research terminals; facilities for food, fuel, repairs, and rest; and places where hazardous materials are loaded and unloaded. 3.3 Enforcement 3.3.1 Types of Enforcement Activities Law enforcement agencies in each state undertake truck-oriented enforcement activities including the following: â¢ Routine enforcement of state and local traffic laws that apply to all vehicles. â¢ Enforcement of truck size and weight regulations. â¢ Inspections for enforcement of the Federal Motor Carrier Safety Regulations and the U.S. DOT hazardous materials regulations for Interstate commerce. â¢ Inspections for enforcement of state motor carrier safety regulations and hazardous materials regulations for intrastate commerce. Many states have adopted all or part of the Federal Motor Carrier Safety Regulations and the U.S. DOT hazardous materials regulations that apply to Interstate commerce for application to
20 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide intrastate commerce as well. In many states, federal agencies have delegated their enforcement of federal regulations within that state to a state law enforcement agency, such as the state police or highway patrol. Many state law enforcement agencies have a motor carrier enforcement unit specifically responsible for enforcement of motor carrier safety and hazardous materials regulations. Law enforcement agencies typically conduct truck enforcement activities in three ways: â¢ Routine stopping of trucks when a patrol officer observes a violation. â¢ Random stopping of trucks for inspection at locations where a need for enforcement has been identified. â¢ Systematic stopping of all or most trucks at established weigh stations. The relationship of highway design to each of these three types of enforcement activities is discussed in the next three sections. 3.3.2 Routine Stopping of Trucks for Observed Violations Law enforcement officers routinely stop trucks when a violation is observed. Observed viola- tions could include violations of state or local traffic laws (e.g., speeding, improper lane changing) or violations of motor carrier safety or hazardous materials regulations (e.g., equipment viola- tion, improper placarding). Such violations may occur anywhere on the highway system. Law enforcement officers prefer to stop trucks at locations with full paved shoulders or that otherwise provide a good place for both the truck and the officerâs vehicle to stop. If a truck is stopped on an unpaved, soft shoulder, the truck may become mired and require a tow truck to extricate it, which consumes time for both the officer and the truck driver. If the shoulder is not wide enough, the truck may encroach on the traveled way when stopped. Trucks on the NN are permitted to be up to 8.5 ft in width, so a truck stopping on an 8-ft shoulder may still encroach on the traveled way. Therefore, on truck routes where paved shoulders are not wider than 8.5 ft, transportation agencies may want to provide paved turn- outs at intervals or other appropriate stopping areas large enough for a truck and at least one other vehicle. The space should be sufficient enough for an officer to perform an inspection. A typical turnout size might be 200 ft by 20 ft. Provision of turnouts at intervals also provides operational flexibility to the roadway, such as a stopping area for vehicle breakdowns or an off-road site for crash investigations. 3.3.3 Enforcement Sites for Random Stopping of Trucks Law enforcement agencies often target specific roads for random inspection of trucks. Such roads may include truck routes with large volumes of trucks or roads that appear to be used frequently by truckers avoiding a fixed enforcement site, such as a weigh station. Transportation agencies can assist law enforcement agencies by providing off-road areas specifically for enforce- ment activities on roads where random enforcement is needed. Random enforcement activities could include vehicle inspections, review of driver logs, review of OSOW permits, and weighing the truck with a portable scale. An ideal site for random enforcement would include the following: â¢ A level, paved roadside area sufficiently large for enforcement activities. â¢ A hard, stable surface suitable for use of a portable scale. â¢ A traffic barrier between the enforcement area and the roadway to protect the officers, the truck driver, and their vehicles.
Planning for Truck Routes and Other Related Considerations 21 â¢ Sufficient space for trucks completing inspections to pull around trucks in ongoing inspections and for trucks placed out of service to remain parked. Figure 5 shows a photograph of a typical site for random enforcement. 3.3.4 Weigh Stations Fixed weigh stations also play a key role in truck enforcement activities. Weigh stations are typically provided on the highway right of way at state ports-of-entry and at other strategic locations on intercity truck routes. Weigh stations not only provide a facility for quickly deter- mining truck gross weights and axle loads, but they can also provide space for vehicle inspec- tions, review of driver logs, review of OSOW permits, and parking for vehicles placed out of service. Some state design manuals include information on weigh station design. Advanced technology can enhance the effectiveness and efficiency of weigh station operations. A state-of-the-art weigh station may include the following: â¢ Weigh-in-motion sensors on the roadway in advance of the weigh station to detect potentially overweight vehicles. â¢ Transponders to communicate signals to the truck driver (e.g., bypass/enter) in advance of the weigh station. â¢ Sensors at the weigh station entrance to detect overheated brakes. â¢ Cameras to automatically read the truckâs license plate. â¢ Cameras to automatically read the truckâs inspection sticker to determine whether it has been inspected recently. Technology of this type allows law enforcement officers to quickly assess which trucks should be stopped for weighing and inspection and which should be waved through. 3.4 Roadway Maintenance The presence of trucks on roadways generates unique maintenance issues as a result of heavy loads and wide turning paths. Access management treatments may also present mainte- nance challenges. Figure 5. Typical roadside area used for random truck enforcement. (Photo source: Google Earth.)
22 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide 3.4.1 Encroachment on Shoulders or Roadside Areas Damage to areas outside the traveled way as a result of encroachment by turning trucks is a key maintenance concern for transportation agencies. Some access management techniques require turning maneuvers. Common elements that are damaged due to truck encroachment include shoulders, curbs, drainage features, areas behind the curb, pedestrian button pedestals, and median barrier attenuators. Figure 6 shows rutting behind curbs at a roundabout approach and outside a loon at a median U-turn roadway. Damage to curbing on a roundabout center island is shown in Figure 7. Designers need to utilize turning templates in CADD software in areas where trucks are prevalent. Providing a traversable path for trucks will help mitigate damage resulting from Figure 7. Curb damage on center island of a roundabout. (Photo source: MRIGlobal.) Figure 6. Rutting resulting from truck encroachment at a roundabout approach and rutting resulting from truck encroachment at a loon. (Photo source: MRIGlobal.)
Planning for Truck Routes and Other Related Considerations 23 encroachment. In situations where a large curb return radius is not practical, adding reinforced pavement behind a mountable curb will prevent rutting behind the curb and damage to the curb. This strategy should only be done in situations where pedestrians are not anticipated to be using the pavement behind the curb. 3.4.2 Snow Removal In areas where snow is expected annually, designers should consider snow storage in the vicinity of intersections and other design elements used by trucks. Snow removal and road- way treatment operators should be trained on how to safely remove snow and treat innovative intersection and interchange designs. Clear Roads Pooled Fund Project 14-03 is developing a training video and manual for the best practices and techniques in clearing different inter- change configurations and other geometric layouts (Qi 2018). 3.4.3 Additional Considerations Innovative access management treatments, such as indirect left-turn movements discussed in Section 4.3.6, and innovative interchange designs, discussed in Section 4.4, often need extensive signing. Transportation agencies should train maintenance personnel on placement of these signs and should plan for the additional maintenance needed to maintain the signs. Where flexible delineator posts are used to separate traffic lanes, maintenance crews should be prepared to replace the posts more often if large truck volumes are present. Pavement markings tend to wear more quickly where there are large truck volumes, so more frequent restriping may be needed. Rutting of pavement and development of pot holes are more common on roadways with heavy truck use. It is recommended to use reinforced pavement for turn lanes because of added stresses caused by deceleration of heavy loads and lateral forces resulting from turning trucks. 3.5 Driveway Permits A driveway permit is âa legal document that grants approval to construct and operate a driveway or other access of a certain design at a specific location on a given roadway for specific purposesâ (Koepke and Levinson 1992). Driveway permits âare typically required when any new access point is to be constructed or when an existing access point needs to be modified within the right-of-wayâ (Williams 2002). The objectives of regulating access points through driveway permitting include the following (Williams 2002): â¢ Maintaining the functional integrity of the state highway system. â¢ Encouraging uniformity of standards and practices. â¢ Maintaining smooth and efficient traffic flow. â¢ Enforcing minimum distances between driveways. â¢ Minimizing conflict points. â¢ Maintaining appropriate sight distances on the state highway system. â¢ Monitoring driveway design. â¢ Providing for motorist and pedestrian safety. â¢ Maintaining highway right-of-way drainage. â¢ Facilitating public access to state rights of way. â¢ Promoting close cooperation with local governments in site planning. â¢ Preserving transportation corridors. â¢ Protecting the public investment in the state highway system.
24 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide The driveway permitting process not only establishes the number of driveways a property may have, but it also influences driveway locations. Driveway permits often include conditions, such as provision of turn lanes, wide turning radii, and so forth. For sites where truck access is neededâsuch as retail and wholesale businesses and manufac- turing facilities that need truck pickups and deliveriesâconsideration of internal site circulation for trucks must be taken to ensure the internal site operation will not result in truck spillback onto the public street or highway. Most transportation agencies request an internal site circulation plan as part of a driveway permit request for commercial or industrial facilities. The internal site circulation plan typically includes the following: â¢ Number, location, and width of driveways. â¢ Type of driveway operation (one-way/two-way, right-in/right-out versus all movements, including left turns). â¢ Location of loading docks or delivery doors. â¢ Internal site circulation routes between driveways and loading docks or delivery doors, in relation to buildings and parking areas. For many sites, transportation agencies typically allow only one driveway but may make an exception to this policy based on internal site circulation needs. Transportation agencies have indi- cated that gas stations can be challenging sites for internal circulation because they are relatively small sites, and they need to accommodate truck-turning maneuvers and customer circulation when trucks are parked during deliveries. For this reason, two driveways may be permitted for gas stations. In some cases where two driveways are provided, however, transportation agencies may require that one driveway operate as an entrance-only driveway and the other as an exit- only driveway. Another option is to locate one of the driveways on a side street if feasible. NCHRP Synthesis 304: Driveway Regulation Practices suggests that, during the driveway permit application process, it is important to review what design is required to accommodate the demand for the development (Williams 2002). The access provided should meet the design criteria of the roadway, especially on truck routes. The Access Management Application Guidelines (AMAG) recommend that, when evaluating access permits, agencies assess the type, size, and number of trucks that would use a driveway to ensure, where practical, that these vehicles do not have an undue impact on the traffic stream (Dixon et al. 2016). The AMAG state that âthe safety and operational impacts on pedestrians, cyclists, and transit should be explicitly considered when an application for a driveway is reviewed.â At locations where pedestrian volumes are high, the number and width of driveways should be minimized. Also, at locations where existing or anticipated pedestrian volumes are high and large trucks will be making deliveries, the AMAG suggest that agency staff work with the developer to establish time periods for deliveries to minimize interactions between pedestrians and trucks. 3.6 Oversize/Overweight Permits The movement of OSOW trucks generally requires operators to obtain a permit from the state DOT. Permits are issued for trucks transporting indivisible loads. If a load is divisible, that load is expected to be transported within the normal truck size and weight limitations. FHWA (2015) has published a compilation of truck size and weight limit laws showing the maximum sizes and weights of trucks that can operate without permits in each state. Each state has its own rules about how permits are applied for and issued, how routes for OSOW trucks are determined, and what time-of-day or other restrictions may apply to OSOW truck movements. State DOTs are generally moving toward online permitting systems. Some online systems provide online interactive tools that assist truck operators in determining a route based on OSOW truck dimensions.
Planning for Truck Routes and Other Related Considerations 25 The OSOW permit may include time restrictions to when the load can move within the jurisdiction. Some states restrict movement in urban areas during designated peak hours. Some states prohibit movement of certain OSOW loads during nighttime hours. However, the opposite also occurs; in one particular metropolitan area, OSOW loads may only move during nighttime hours. One state reports that their biggest problem with oversize permit trucks is bridge hits from overheight trucks. However, another state reports that they get very few bridge hits from permit trucks and that most bridge hits result from nonpermit trucks (Potts et al. 2019). 3.6.1 Routing Considerations Routing considerations for overweight trucks focus primarily on the structural capacity of bridges. Routes for overweight trucks should not include bridges that cannot carry the trucksâ weight. Most access management treatments are not an issue for oversize trucks traveling straight through the treatment. Where trucks must turn at an intersection, the pavement width and curb return radius should be assessed. Indirect left-turn treatments may present challenges for oversize trucks making left turns (see the following and Section 4.3.6). Some intersection and interchange features are easier for oversize trucks to traverse than others. Routing considerations include physical conditions, such as overhead structures, cross section widths, overhead traffic signals, and roundabouts. Particular attention should be paid to horizontal clearance and vehicle undercarriage clearance at roundabouts. Routing considerations may also include whether there are locations that may not be compatible with the truck movement, such as environmentally sensitive areas. Special events, such as marathons and road races, may create the need for imposing temporary restrictions on oversize truck movements because of competing demands for the road space. Any type of overhead structure should be examined in planning an oversize truck route to make sure the clearance height is adequate. The number of lanes, lane widths, and widths of bridge structures should also be considered. Locations where the normal 1.5-ft lateral offset outside the edges of the traveled way is not provided should be considered. Traffic-signal span wires present a unique challenge for overheight trucks. Some agencies have reported the need to raise span wires on hot days in order to get an overheight load to clear an overly sagged span wire. Roundabouts should be examined carefully during the route planning to make sure the oversize truck can traverse the roundabout. Roundabouts should be designed to handle oversize trucks up to a certain maximum size on routes that experience OSOW loads on a regular basis; this can be accomplished with horizontal clearances and truck aprons surrounding the central island without affecting the operation of the roundabout for smaller vehicles. The online permitting systems of some states include automated routing tools that can be utilized for OSOW trucks up to a specific maximum size and weight. Larger and heavier OSOW trucks require manual assessment of routes. Other states prefer to retain OSOW routing as an entirely manual process to ensure that no key factors in the routing decision are overlooked. Routes for OSOW trucks should be planned in consultation with local municipalities and MPOs. 3.6.2 Route Continuity Infrastructure improvement projects should be planned to maintain route continuity for OSOW permit trucks. Part of the project planning process should be to investigate past OSOW permit operations and ensure that new projects do not introduce new restrictions that create
26 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide discontinuities in routes likely to be used by future OSOW permit operations. As part of the planning process, route continuity and available alternative routes should be analyzed, and routes likely to be used by future OSOW permit operations should be preserved with respect to the following: â¢ Vertical and horizontal clearance limitations at structures. â¢ Bridges with limited structural capacity. â¢ Roundabout geometrics. â¢ Conventional intersection geometrics. â¢ Horizontal and vertical roadway alignments. 3.6.3 Consideration of Intersection and Interchange Design Features Any type of indirect left-turn treatment that requires a truck to make a U-turn may not be functional for an oversize truck. Agencies should avoid routing an oversize load through the U-turn roadways of Restricted Crossing U-Turn (RCUT) and Median U-Turn (MUT) intersection types (see Section 4.3.6). Even where these U-turns are designed with loons to accommodate trucks, many oversize trucks may not be able to complete the U-turn maneuver. Roundabouts (see Section 4.3.7) are often designed to accommodate oversize trucks up to a certain maximum size determined by the designer. Steerable rear axles can assist an oversize truck in traversing a roundabout. In unusual situations, roundabouts may be temporarily closed to other traffic to allow an oversize truck to traverse the roundabout very slowly. Roundabouts may also be designed with a traversable center island in situations where OSOW trucks are common. One state has provided a roadway traversing the center island of a roundabout with lockable gates to ensure that the roadway is only used for oversize truck movements of which the state DOT is aware. Certain interchange configurations (see Section 4.4) are more accommodating to oversize trucks than others. Single-Point Diamond Interchanges (SPDIs) provide large turning radii for left-turning vehicles, which should easily be traversed by oversize vehicles. Diamond inter- changes in rural areas are generally designed with turning radii large enough to handle most oversize trucks. It should be noted though that encroachment into adjacent or opposing lanes of traffic is often required for oversize trucks to complete turning maneuvers and, in some cases, law enforcement assistance may be needed to temporarily stop other traffic and provide a clear turning path for an oversize truck. Diverging Diamond Interchanges (DDIs) with multilane approaches generally work well for oversize trucks. Oversize trucks will most likely need to utilize all lanes of the approaches to complete turning maneuvers. While some intersection and interchange design features are more difficult for oversize trucks to traverse than others, this should not discourage agencies from implementing such treat- ments where they provide traffic operational and safety benefits for traffic as a whole. However, agencies should consider the availability of alternative routes for oversize trucks as part of the design process. 3.7 Truck Parking 3.7.1 On-Street Loading and Unloading Zones Trucks must often stop along roads and streets to make pickups and deliveries at locations where off-road loading and unloading areas are not provided. Where there is a continuing need, transportation agencies can sign curbside loading zones in accordance with the FHWA Manual on Uniform Traffic Control Devices for Streets and Highways (MUTCD) Section 2B.46, Parking
Planning for Truck Routes and Other Related Considerations 27 Standing and Stopping Signs, and mark loading zones on the pavement in accordance with MUTCD Section 3B.19, Parking Space Markings (FHWA 2009). There are many locations where curbside pickups and deliveries need to be made, but no curbside loading zones are provided. Reasons why curbside loading zones may not be provided include the following: â¢ The agency does not mark loading zones as a matter of policy. â¢ Traffic demand is sufficiently high that no curbside parking of any kind is permitted. â¢ Pickups and deliveries at that location are perceived to be infrequent. Businesses typically generate demand for pickups and deliveries whether loading zones are pro- vided or not. Residences also generate pickup and delivery demand and, especially in this age of online shopping, deliveries to multifamily residential buildings have become substantial. Trans- portation agencies should consider how these demands can and should be met in the absence of loading zones. Should illegal curb parking for pickups and deliveries be accepted as undesirable but necessary? Should trucks making pickups and deliveries park in center two-way left-turn lanes and other median areas? Should pickup and delivery times be regulated by local ordinances? Planning for curbside loading and unloading needs should address the following: â¢ Typical delivery vehicle sizes. â¢ Typical duration of delivery stops. â¢ Compatibility with adjacent pedestrian, bicycle, and transit facilities. Consultation with truck operators and local businesses is needed to reach satisfactory plans for loading and unloading facilities where off-street facilities are not available. Designated bicycle and transit facilities should be located to avoid roadways with curbside loading and unloading activities to help minimize conflicts that may occur with truck activities. Freight and Service Activity Generation software (Holguin-Veras et al. 2016) is available to assist in planning for on-street loading and unloading zones and off-street loading and unloading facilities. The software can make estimates of freight and service activities at the Zip Code and establishment levels for the entire United States. 3.7.2 Off-Street Loading and Unloading Facilities Off-street loading and unloading facilities should be encouraged in land development projects through zoning ordinances and review of development impact studies. In dense urban areas, alleys are often provided to allow off-street loading and unloading. Section 3.5 indicates that internal site circulation plans and loading and unloading facilities should be addressed in the driveway permit review process. Many off-street loading and unloading facilities either have gates that can be closed at the discretion of the site owner to restrict trucks from entering or have established entry/exit time schedules. Off-street parking/waiting areas should be provided so that trucks waiting to enter the facility do not need to queue on a public highway. This should be considered in driveway design and in the review of site circulation plans (see Sections 3.5 and 4.5). Planning for off-street loading and unloading should consider the following: â¢ Truck routing and circulation to access loading and unloading facilities. â¢ Location of loading and unloading facilities so that trucks entering the facility (including trucks backing into the facility) do not impede traffic on a traveled way. â¢ Location of loading and unloading facilities so that trucks do not block pedestrian or bicycle facilities, including sidewalks, during loading and unloading operations.
28 Design and Access Management Guidelines for Truck Routes: Planning and Design Guide 3.7.3 Truck Parking Places for Driver Rest There is a nationwide shortage of truck parking places for driver rest. Over-the-road truck drivers are required to take 10 hours off duty following no more than 14 consecutive hours on duty or a cumulative total of 11 hours of driving time during that 14-hour period (49 CFR 395). When approaching the 11- or 14-hour limit, or sooner, truck drivers must find a place to park their vehicle and go off duty. The shortage of parking areas has existed for a long time, but the lack of parking areas has recently become a more critical issue with the new federal mandate for on-vehicle electronic data loggers (EDLs) into which drivers make entries when they come on and go off duty and when they begin and end driving. Before EDLs, when necessary, a driver might take some time to find a safe place to park after the 11th hour of driving or the 14th hour on duty; extending the search for a safe parking place beyond the 11th or 14th hour was illegal, but drivers were unlikely to be cited for this violation. Now, any search for a safe parking place after the 11th or 14th hour is electronically documented as a driver violation. Thus, if a driver enters a truck stop just before the 11th hour of driving or the 14th hour on duty, expecting to remain there for 10 hours off duty, but finds that all parking spaces are taken, any continued search for a safe parking place to spend the off-duty period will constitute a violation of the hours-of-service rules for that driver. Many more drivers are now choosing to park their trucks illegally, in exposed positions on highway shoulders or on ramps, risking a parking citation (a nonmoving violation), rather than an hours-of-service violation. The rest areas provided by transportation agencies typically have limits on the maximum time trucks can remain that are shorter than the required 10-hour off- duty period. The challenge created by the lack of truck parking places is not necessarily the responsibility of transportation agencies to resolve, because most parking spaces for trucks are provided at commercial facilities, such as truck stops. Nevertheless, the lack of truck parking spaces is having undesirable effects on the highway system, so it is certainly desirable that a combination of action by transportation agencies and commercial operators address this issue.