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Gore (road)
Gore (road)
Gore (road)
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Highway exit gore in Gdańsk, Poland, with a transversely lined "theoretical gore", followed by a grass-covered physical one
Two diverging white lines demarcate the theoretical gore of this highway exit on Interstate 40 in Arkansas, with a grass-covered physical gore following it: In this instance, the theoretical gore contains no markings.
Exit gore on Interstate 95 in Connecticut: Note the theoretical gore has been marked with chevrons.

In road and highway construction, a gore (US) or nose (UK)[1] is a triangular plot of land, not to be driven on, where a road forks at the intersection with a second road, or merges on and off from a larger one. Gores at exit ramps occasionally have impact attenuators, especially when an obstruction such as a bridge abutment follows the gore.

The US term "gore" (describing a space) historical, representing a characteristically triangular piece of land, often designated incidentally when two surveys failed to meet. Etymologically, it is derived from gār, meaning spear.[2]

A "virtual" (or theoretical) gore is a triangular-shaped paved space, which may lead to the unpaved area of a larger physical gore. A theoretical gore is commonly marked with transverse or chevron painted lines to discourage being driven on.

In the US, at the "theoretical gore point", a dotted white line becomes a wide, solid-white channelizing line and another wide, solid-white line angles off along the edge of the diverging road, forming an elongated white triangle in front of the gore. This as a "neutral area" with white chevron markings optionally added.[3]

A very old example of a gore surviving as a street name in London is Kensington Gore, long completely built over and reshaped, where now stands the Albert Hall.

See also

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References

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Revisions and contributorsEdit on WikipediaRead on Wikipedia

Gore (road)

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In road and , a gore is the triangular area located between the main roadway and a ramp just beyond where the ramp branches from or merges with the main roadway at an interchange. This area is typically unpaved or marked to prevent vehicular traffic from crossing it, serving to safely separate merging and diverging flows of vehicles and reduce collision risks. Gores are essential elements in freeway and expressway interchanges, where they define the boundary between high-speed mainline traffic and slower ramp movements. There are two primary types: a physical gore, which is a tangible longitudinal point delineated by a barrier, , or unpaved surface that physically inhibits drivers from crossing between the ramp and main roadway; and a theoretical gore point, which marks the hypothetical intersection of the gore's rear edge with the main roadway if it were fully constructed, often used for planning and signing purposes. These features are standardized under the Manual on Uniform Traffic Control Devices (MUTCD), ensuring uniform design across states to enhance driver comprehension and safety. To guide drivers, gores are delineated with pavement markings such as solid white lines, chevron patterns, or transverse bars that extend from the main roadway into the gore area, visually emphasizing the no-crossing zone. Exit gore signs (E5-1 series), typically white-on-green rectangular panels displaying the interchange name or number, are mandated at the gore of every departing ramp on freeways and expressways to provide reassurance to exiting drivers and confirm their location. Driving through or across a gore is prohibited in most jurisdictions, as it endangers separation and can result in citations or accidents, with enforcement emphasized by state departments of transportation. In the , the equivalent feature is commonly termed a "," reflecting regional variations in terminology while serving the same functional purpose.

Definition and Etymology

Definition

In road infrastructure, a gore is a triangular plot of land that is designated as non-drivable, situated at the point where a road forks or merges, most commonly at highway interchanges. This area is defined as the space between the main roadway and a ramp immediately beyond where the ramp branches from or joins the main roadway. Its primary purpose is to provide a physical separation between merging or diverging traffic lanes, ensuring vehicles cannot cross into the zone and thereby maintaining safe traffic flow. Geometrically, a gore forms a triangle bounded by the edges of the main roadway and the connecting ramp. In the United States, the term "gore" is standard in traffic engineering and regulatory contexts, while in the United Kingdom, the equivalent structure is referred to as a "nose." The term "gore" originates from Old English gāra, meaning a corner, point of land, or promontory, historically applied in land surveying to describe wedge-shaped parcels.

Etymology

The term "gore" in the context of road features originates from gāra, denoting a corner, point of , or , which evolved to describe a triangular or wedge-shaped piece of ground or cloth. This usage stems from the Proto-Germanic root *gaizô-, related to a or pointed stick, reflecting the shape's pointed form. By the early 14th century, it applied to triangular patches of fabric, and by the 1640s in New England, it designated omitted strips of in property surveys. In 18th- and 19th-century land surveying, particularly in , "gore" specifically referred to narrow, triangular parcels resulting from inaccuracies or discrepancies in boundaries between adjacent properties, often left unincorporated due to surveying errors. These gores were common in colonial land grants and early American territorial divisions, where imprecise measurements created irregular slivers of unclaimed land. The term's application highlighted the geometric similarity to a spearhead or . In , the equivalent feature is commonly termed a "."

Design Features

Theoretical and Physical Gores

In highway design, the theoretical gore represents the conceptual triangular point where begin to separate or merge, defined as the apex of the painted gore stripes where the through lanes and ramp lanes achieve full width. This point serves as a for measuring ramp lengths and ensuring operational continuity, such as maintaining driver expectations for lane balance and visibility during transitions. The physical gore, in contrast, is the tangible area beyond the theoretical gore, marking the actual boundary where the paved ramp surface ends and transitions to unpaved or non-traveled , often extending to barriers, features, or roadside elements. This area forms the base of the triangular configuration, providing a buffer that discourages unintended entry while accommodating drainage and needs. Construction of gores typically involves tapered pavement edges using standard roadway materials such as asphalt or concrete to form the theoretical gore's integrated surface, ensuring a smooth transition for vehicles. The physical gore is often left unpaved, landscaped with grass or low-maintenance vegetation, or stabilized with natural materials to promote recovery zones and aesthetic integration, while concrete barriers or guide rails may delineate its limits in high-traffic areas. Gore dimensions vary based on design speed, traffic volume, and interchange type, generally starting narrow at the apex—often 0 to 50 feet wide—and widening progressively along the ramp to full widths of 6 to over lengths of 300 to 800 feet from the gore to the painted tip. For instance, entrance ramp gores may extend 400 to 800 feet from the physical gore to the merging point, while diverge angles of 2° to 5° influence the overall taper length to optimize visibility and safety.

Markings and Signage

In the United States, pavement markings for gores typically transition from dotted edge lines to solid wide lines at the theoretical gore point, guiding vehicles away from the neutral area and forming a channelizing that delineates the triangular gore . These markings, often 6 to 8 inches wide for solid lines, begin at least 0.5 miles in advance of drops on freeway exit ramps to provide early visual cues. Optional white chevron crosshatch markings may be placed within the theoretical gore's neutral area to emphasize the no-drive zone, with chevrons oriented to point toward approaching traffic for enhanced visibility and deterrence. These diagonal stripes, spaced to fill the paved island, supplement the solid boundary lines and are particularly used in high-speed interchanges to discourage errant vehicle paths. Signage standards under the Manual on Uniform Traffic Control Devices (MUTCD) recommend regulatory signs such as the "DO NOT DRIVE ON SHOULDER" (R4-17) near gore areas where shoulders adjoin ramps, informing drivers that shoulder use is prohibited to protect the gore island. Ramp advisory signs, including speed limit plaques and warning diamonds for merging traffic, are also placed in advance of and at the gore to alert drivers to the configuration. Internationally, variations exist; in the , similar nose markings at slip road gores use white chevron markings under the Traffic Signs Regulations and General Directions (TSRGD), with Diagram 1042 prescribing 150-200 mm wide reflective white stripes bordered by solid white lines to mark prohibited entry areas at grade-separated junctions. These chevrons, mandatory for motorways, taper into the merge or diverge and incorporate red reflective studs for nighttime visibility.

Types of Gores

Merge Gores

Merge gores are triangular areas at the terminus of entrance ramps where vehicles accelerate and blend into the mainline freeway traffic. Their primary function is to allow vehicles entering from on-ramps to merge safely without crossing existing lanes, thereby minimizing conflicts and maintaining the flow of higher-speed through traffic. According to the AASHTO Green Book (2018), this design separates merging streams from the mainline, providing a dedicated space for drivers to adjust speed and position. In terms of design specifics, the gore's apex points toward the mainline, forming a narrow tip at the point of initial separation, while the triangle widens progressively along the merging ramp to accommodate vehicle trajectories. This typically includes adjacent acceleration lanes to facilitate the transition, with base widths of 4 to 8 feet, limited to the sum of shoulder widths on the ramp and freeway plus a narrow physical , adjustable for design speeds exceeding 60 mph. FHWA guidelines emphasize that such configurations, often spanning 400-800 feet from the physical gore to the painted merging tip, enhance capacity and reduce bottlenecks in merge areas. The traffic flow through a merge gore prioritizes an zone where entering reach mainline speeds, typically 55-70 mph, before the gore's end to ensure seamless integration. Acceleration lengths are determined by factors such as initial speed, grade, and vehicle type, with desirable lengths of up to 1,200 feet for high-volume scenarios to support free-flow speeds around 66 mph. This setup distributes merge points and improves overall efficiency, as evidenced by simulations showing throughput increases of 6-9% under congestion. Merge gores are commonly implemented at on-ramps in urban interchanges, where ramp grades and traffic volumes dictate variable lengths; for instance, interchanges often feature spacings of 1,600-2,600 feet between entry and exit points to optimize merging. A practical example is the split merge design on I-66 in , which incorporates gore areas to handle high volumes, resulting in reduced delays by 5.5% and improved operational performance. These applications align with AASHTO recommendations for spacings of at least 1,000 feet between successive ramps to prevent interference.

Diverge Gores

Diverge gores are triangular areas in interchanges where separates from the mainline roadway to enter an exit ramp, facilitating the safe deceleration and of vehicles heading off the freeway while maintaining flow for through . The primary function of a diverge gore is to physically and visually separate decelerating exiting vehicles from continuing mainline , reducing conflict points and allowing drivers to initiate changes upstream of the gore apex. This separation is critical in high-speed environments, where exiting drivers must reduce speed from typical freeway rates of 70 mph or higher to safer ramp velocities, often around 30-50 mph. In design, the gore's apex points toward the start of the exit ramp, forming a that widens along the mainline direction to provide a that expands with distance from the point. Deceleration are integral to diverge gores, enabling vehicles to slow gradually without impeding mainline traffic; according to AASHTO guidelines in the Green Book, minimum deceleration lane lengths vary by speeds—for instance, 435 feet for a 70 mph mainline and 50 mph ramp in a tapered configuration, excluding the taper itself. Taper lengths for the initial separation typically range from 500 to 1,000 feet, scaled to the speed to ensure smooth trajectory paths for exiting vehicles, with parallel-type designs using longer, straight lanes and shorter tapers compared to tapered types. The reserved gore area length increases with mainline speed, from 25 feet at 40 mph to 70 feet at 80 mph, to accommodate visibility and safety features like delineators. Traffic flow in diverge gores prioritizes orderly lane changes for exiting vehicles, with the widening triangular shape allowing drivers to merge rightward over the taper distance while through traffic remains unobstructed. This configuration supports deceleration in phases—, control, in-gear slowing, and braking—minimizing rear-end risks and erratic maneuvers. Diverge gores are prevalent at off-ramps in freeway systems worldwide, particularly in space-constrained urban or mountainous areas where sharp-angle diverges (2-5 degrees) necessitate compact designs to fit while meeting standards. Pavement markings, such as 8-12 inch wide white lines and chevrons in the gore, aid in guiding drivers during these transitions.

Safety and Regulations

Common Hazards

Gore areas in interchanges, where lanes merge or diverge, present significant challenges due to the and high-speed traffic dynamics. These triangular zones often become focal points for conflicts as vehicles navigate , deceleration, or changes, increasing the of collisions compared to straight roadway sections. Primary hazards in gore areas stem from erratic driver maneuvers, such as attempting to cross the gore to correct for a missed exit or merge, which frequently results in sideswipe collisions or wrong-way driving incidents. At diverge gores, where traffic splits, drivers may overrun the edge due to deceleration errors, leading to run-off-road crashes into barriers or embankments. In merge gores, speed mismatches between entering and through traffic heighten the potential for rear-end collisions as vehicles accelerate to match speeds. These patterns are exacerbated by the gore's geometry, which limits escape space for corrective actions. Statistical data underscores the disproportionate crash risk in gore areas compared to other roadway sections, according to analyses. Studies of urban freeways indicate elevated crash rates in gore sections relative to adjacent mainline segments, with sideswipes and run-off-road events common in these zones. Nighttime conditions amplify these risks due to reduced in poorly lit gores. Contributing factors to gore hazards include driver distraction, a leading cause of crashes in interchange areas per reports, often leading to unintended lane departures into the gore. Unfamiliarity with interchange layouts, particularly for non-local drivers, further elevates risks, as does the presence of sharp gore angles that create additional conflict points between merging and diverging paths. Adverse weather, such as rain or , reduces traction and , compounding these issues and resulting in hydroplaning or misjudged maneuvers within the gore.

Mitigation Strategies

Mitigation strategies for gore areas encompass a range of , regulatory, and operational interventions aimed at minimizing crash risks and enhancing in these transitional zones. These measures the vulnerability of gores to errant vehicle incursions, such as those from crossing maneuvers, by prioritizing physical protection, legal deterrence, and environmental cues. solutions focus on installing impact attenuators at gore ends, particularly near fixed objects like bridge abutments or supports, to absorb and redirect vehicle impacts. Crash cushions and guardrails serve as primary devices, decelerating vehicles over a controlled distance to prevent penetration into hazards; for instance, energy-absorbing systems are recommended for urban freeway gores where space is limited. These installations comply with standards ensuring compatibility with roadside barriers, reducing injury severity in high-speed environments. Regulatory measures enforce strict prohibitions on driving within gores to prevent unauthorized crossings. Most U.S. states codify these rules in vehicle codes, imposing fines ranging from $100 to $1,000 for violations, depending on jurisdiction; for example, Arizona's ARS §28-644 explicitly bans driving over or parking in gore areas, treating it as a civil infraction. Additionally, the Manual on Uniform Traffic Control Devices (MUTCD) mandates exit gore signage, such as overhead Exit Gore signs with route shields, to clearly delineate boundaries and guide exiting traffic. Operational improvements enhance gore safety through sensory and informational aids. Rumble strips, milled into the pavement within physical gores, provide tactile and auditory warnings to drifting drivers, particularly effective in preventing lane departures near ramps. installations, including high-mast poles or delineators, improve nighttime visibility in gores and can reduce nighttime crashes by up to 50% at interchanges. For high-volume interchanges, dynamic signage—such as variable message signs—alerts drivers to congestion or hazards in real-time, integrating with systems. Best practices, as outlined by the (FHWA), emphasize designing gores with sufficient lengths based on ramp design speed—typically 200 to 600 feet or more in urban settings—and strategic barrier placements to allow and shield fixed objects. These guidelines, aligned with AASHTO standards, prioritize clear zones free of obstacles and integrate attenuators to protect against errant vehicles, promoting a layered approach to safety. Emerging technologies, such as vehicle-to-infrastructure (V2I) systems, are being explored to further mitigate hazards through real-time warnings as of 2023.

Historical Development

Origins in Land Surveying

In colonial America during the 1600s and 1700s, the term "gore" referred to residual triangular or irregularly shaped parcels of that emerged as byproducts of metes-and-bounds practices, where boundaries were defined using natural landmarks and directions rather than a uniform grid system. These gores typically resulted from errors in early patents or overlapping claims, particularly when rectangular grants from colonial authorities intersected imperfectly, leaving narrow, wedge-like "spearhead" areas too small or unproductive for practical farming or settlement. In regions like , where dense forests and rugged terrain complicated measurements, surveyors using chains and rudimentary instruments often failed to perfectly align converging lines, creating these unintended slivers that were documented in records as gores. By the 1800s, gores were a common feature in American land division, especially in the original colonies and areas, where they represented the limitations of pre-grid methods inherited from European traditions. These parcels were often barren or rocky, rendering them economically marginal and leading to disputes over ownership or ; in many cases, they were granted by legislatures as compensatory land to veterans or petitioners, further complicating the landscape. Notable examples appear in 19th-century U.S. land records from , where the state once contained over 60 such gores—irregular remnants from town boundary surveys conducted in the late 1700s and early 1800s by figures like surveyor general James Whitelaw. Townships in Essex and Chittenden Counties, such as Avery's Gore and Warren's Gore, illustrate these formations, with some annexed to adjacent municipalities decades later to resolve administrative issues.

Evolution in Road Design

The adoption of gores in highway engineering began in the United States during the 1920s and 1930s, coinciding with the emergence of controlled-access roads and early interchanges designed to separate conflicting traffic flows. The Woodbridge Cloverleaf in New Jersey, constructed in 1929, represented one of the first implementations of such features in American road design, where triangular gore areas facilitated safe ramp separations at grade-separated junctions. These elements were integrated into initial standards by the American Association of State Highway Officials (AASHO), which published early guidelines on geometric design in the 1930s to promote uniformity in managing traffic at diverging points on limited-access facilities. Following , the established the , which standardized gore configurations nationwide to enhance safety, particularly at diverge points where vehicles transitioned from high-speed mainlines to ramps. AASHO's "Blue Book" (A Policy on Geometric Design of Rural Highways, 1954, updated in subsequent editions) emphasized gore tapers and areas to minimize conflict zones, reflecting a focus on accommodating growing vehicle volumes and speeds on the new network. In the 1980s and 2000s, the (FHWA) revised gore design criteria based on analyses of crash data from interchanges, leading to improvements in taper lengths, barrier placements, and delineation to reduce nighttime and exit-related incidents. These updates were incorporated into the AASHTO "Green Book" (A Policy on Geometric Design of Highways and Streets), with editions from 1984 onward providing detailed specifications for gore areas, including minimum widths and treatments informed by empirical safety studies. Globally, similar developments occurred in the , where "noses" (the British term for gores) evolved in motorway design starting in the as part of the expanding network of grade-separated routes. Initial layouts drew from U.S. influences and local trials, with the Department of Transport's Technical Memorandum H18/75 (1975) formalizing nose lengths and tapers at 80 meters minimum (or 100 meters with lane drops) using a 1:15 ratio to optimize diverging flows. Subsequent standards, such as TD22/86 (1986) and TD22/92 (1992), refined these elements through safety-driven adjustments to handle higher traffic densities and , maintaining core dimensions while introducing flow-based selection tools.

References

  1. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/mutcd11thedition.pdf
  2. https://www.txdot.gov/manuals/des/rdw/chapter-15-grade-separations-and-interchanges-/15-7-ramps---direct-connectors-/15-7-3-ramp-geometrics.html
  3. https://azdot.gov/blog-article/crossing-gore-area-not-allowed
  4. https://www.sabre-roads.org.uk/wiki/Gore
  5. https://mutcd.fhwa.dot.gov/htm/2009/part2/part2e.htm
  6. https://highways.dot.gov/safety/other/older-road-user/handbook-designing-roadways-aging-population/chapter-3-interchanges
  7. https://www.roads.org.uk/dictionary
  8. https://www.etymonline.com/word/gore
  9. https://cdn.ymaws.com/www.nysapls.org/resource/resmgr/2022_conference/handouts/gores%2C_gaps%2C_overlaps.pdf
  10. https://mutcd.fhwa.dot.gov/htm/2009/part3/fig3b_09_2_longdesc.htm
  11. https://cmfclearinghouse.fhwa.dot.gov/studydocs/nchrp_rpt_687.pdf
  12. https://www.dot.ny.gov/divisions/engineering/design/dqab/hdm/hdm-repository/rev_64_HDM_Ch10.pdf
  13. https://dot.nj.gov/transportation/eng/CADD/v8/pdf/StandConstDetails.pdf
  14. https://dot.ca.gov/-/media/dot-media/programs/design/documents/chp0900-032020.pdf
  15. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/part3.pdf
  16. https://mutcd.fhwa.dot.gov/htm/2009/part3/part3b.htm
  17. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/Chapter2b.pdf
  18. https://mutcd.fhwa.dot.gov/pdfs/11th_Edition/Chapter2c.pdf
  19. https://assets.publishing.service.gov.uk/media/5c4ace6ded915d38a0611abc/traffic-signs-manual-chapter-05.pdf
  20. https://www.codot.gov/business/designsupport/bulletins_manuals/2023-cdot-roadway-design-guide/chapter_10_grade_separations_and_interchanges.pdf
  21. https://www.fhwa.dot.gov/publications/research/operations/20008/20008.pdf
  22. https://www.fhwa.dot.gov/publications/research/safety/humanfac/01103/ch2.cfm
  23. https://wsdot.wa.gov/publications/manuals/fulltext/m22-01/1360.pdf
  24. https://pmc.ncbi.nlm.nih.gov/articles/PMC10725867/
  25. https://rosap.ntl.bts.gov/view/dot/86118/dot_86118_DS1.pdf
  26. https://www.dot.ny.gov/divisions/engineering/design/dqab/hdm/hdm-repository/ch10atten.pdf
  27. https://www.odot.org/traffic/pdfs/AttenuatorGuideline.pdf
  28. https://www.azleg.gov/ars/28/00644.htm
  29. https://trafficlawguys.com/civil-traffic-violations/driving-over-gore-area-ars-28-644a2/
  30. https://dot.ca.gov/-/media/dot-media/programs/research-innovation-system-information/documents/preliminary-investigations/exit-gore-signs-pi-12-12-13-revised-a11y.pdf
  31. https://www.txdot.gov/manuals/des/rdw/chapter-4--basic-design-criteria/4-10-cross-sectional-elements/4-10-6-rumble-strips.html
  32. https://highways.dot.gov/sites/fhwa.dot.gov/files/2022-09/fhwa_handbook2012.pdf
  33. https://www.fhwa.dot.gov/publications/research/safety/17048/17048.pdf
  34. https://static.tti.tamu.edu/tti.tamu.edu/documents/0-6120-1.pdf
  35. https://austroads.gov.au/publications/road-design/agrd06-10/media/AGRD06-10_Guide_to_Road_Design_Part_6_Roadside_Design_Safety_and_Barriers.pdf
  36. https://newenglandhistoricalsociety.com/northern-new-england-has-gores-who-knew/
  37. https://vtdigger.org/2017/03/26/then-again-a-use-for-vermonts-leftover-bits-and-pieces/
  38. https://www.blm.gov/sites/default/files/histrect.pdf
  39. http://www.hunterresearch.com/woodbridge-cloverleaf
  40. https://onlinepubs.trb.org/onlinepubs/circulars/ec003/ch31.pdf
  41. https://www.fhwa.dot.gov/programadmin/interstate.cfm
  42. https://mbtaonline.org/wp-content/uploads/2024/12/0-Geometric-Design-Past-Present-Future_Elizer_Maine-Trans-Conf_Dec-5-24.pdf
  43. https://nacto.org/wp-content/uploads/flexibility_in_highway_design.pdf
  44. https://www.researchgate.net/publication/237258063_A_Critical_Review_of_the_Standards_and_Design_Processes_for_Motorway_Diverges_in_the_UK
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