NGT Non-Gating W-Beam End Terminal MASH TL-3 11.4m

NGT Non-Gating W-Beam End Terminal MASH TL-3

The NGT is a tangent, re-directive and non-gating end terminal for W-beam guardrail, tested to AASHTO MASH 2016 Test Level 3 and eligible for Federal-aid reimbursement under FHWA letter CC-178.

Conventional energy-absorbing terminals consistently stop end-on impacts only at shallow angles. The NGT brings errant vehicles, from small cars to pickups, to a controlled stop for end-on impacts up to 15°, and its length of need begins at Post 2, only 6'-3" (1.9 m) from the first post. This gives road designers more flexibility where hazards, slopes or limited space sit close to the end of the guardrail.

Why non-gating

Conventional gating terminals decelerate vehicles that hit the end at approx. ±3°. At larger angles the vehicle gates behind the guardrail at speed and can travel approx. 150 ft (46 m), into the very hazards the guardrail is meant to shield. Their length of need starts 12-18 ft (3.7-5.5 m) from the end, they depend on a traversable clear zone behind the barrier, and the rail can spear into the vehicle.

85% of off-road terminal crashes occur at angles of 15° or less, and the NGT stops them. US FARS data from 2018 shows approx. 1,000 fatal crashes involving a guardrail impact, approx. 250 of them with the most harmful event behind the barrier: a fixed object, a slope, water or a rollover. For the US, non-gating terminals are estimated to save 200+ lives per year against a societal cost of USD 2.36 billion annually (fatalities only); replacing every terminal in the US within one year would still give a benefit-cost ratio above 1.0.

• Stops end-on impacts up to 15° instead of approx. ±3°

• Length of need from 6'-3" (1.9 m) instead of 12-18 ft

• Less clear zone and earthwork needed behind the barrier

• No spearing

• Crash tested at up to 77.5 mph (124.7 km/h) against 62 mph for conventional terminals

Features

• MASH 2016 TL-3 tested, all seven required tests passed (3-30, 3-31, 3-32, 3-33, 3-34, 3-35, 3-37b)

• FHWA eligibility letter CC-178

• Non-gating for end-on impacts up to 15°

• Length of need from Post 2, 6'-3" (1.9 m) from Post 1

• High-speed testing within all MASH preferred criteria at up to 77.5 mph (124.7 km/h)

• Tangent terminal, no offset required

• 8 unique part types, 22 parts in total excluding fasteners

• Installs with standard guardrail equipment in approx. 45 minutes or less

• Anchor rail, shelf bracket and hardware may be reused after impact

Technical data

• Test standard: AASHTO MASH 2016, TL-3 (100 km/h)

• Terminal length: 37'-6" (11.4 m), anchor post to Post 10

• Pay length options: 37.5 ft (11.4 m), 40 ft (12.2 m), 50 ft (15.2 m)

• Compatible guardrail: strong-post W-beam (MGS) with 8" or 12" blockouts

• Rail height: 31" ± 1" (787 ± 25 mm) above finished grade

• Post spacing: 6'-3" (1.9 m) anchor post to Post 1 and Post 1 to Post 2; 3'-1.5" (0.95 m) Posts 2-9

• Posts: galvanised steel, W6x9 plug-welded posts 1-9, W8x15 anchor post

• Impact head: 8 ft x 14-13/16" x 20" (2.44 m x 376 mm x 508 mm), approx. 91 kg

• Offset / flare: no offset required; 1-2 ft straight flare over 50 ft recommended, max. 25:1

• Connection to rigid barriers via a stiffness transition

Fields of application

Guardrail ends on high-speed roads where a vehicle gating through the terminal would reach a hazard: bodies of water, steep slopes, bridge piers, trees or other fixed objects close to the guardrail end, and locations with too little space for a conventional length of need.