Service · Road restraint
Guardrail end terminals: how each run starts and ends safely
The end terminal is the piece that starts and finishes a run of metal guardrail. SinalServ installs turned-down, energy-absorbing, flared, offset and trailing-end terminals in Brazil, chosen for the speed and impact angle of each stretch.
Sta. 01 · Function
Why does the terminal decide how safe the guardrail is?
The terminal decides how safe the guardrail is because the end of the run is the most dangerous point of the system. An unsuitable terminal can spear the vehicle, vault it or roll it over in a head-on or angled impact; the right terminal prevents all three outcomes.
Every restraint system is started and finished with features that reduce the effects of an impact. That is why choosing the terminal is essential for the installed system to be safe: the line of rails protects those who hit it from the side, but those who arrive head-on hit the terminal first.
Leading and trailing terminals, like the systems themselves, must meet the evaluation criteria of the applicable technical standards for the speed and impact angle expected on the stretch. The client specifies which device to use.
Sta. 02 · Classification
What is a gating and a non-gating terminal?
Under NCHRP 350 and MASH criteria, terminals are classified as gating or non-gating. The difference is what happens when a vehicle hits the terminal at an angle, before the point where the guardrail starts to redirect.
Lets the vehicle pass through
Allows a vehicle that hits the nose or side of the unit at an angle, before the beginning of length of need, to pass through the unit. Requires a clear runout area behind the terminal.
Redirects along its full length
Can redirect a vehicle that hits the nose or side of the unit at an angle along its full length, from the impact head onwards.
Sta. 03 · Types
Which terminal types does SinalServ install?
SinalServ installs five types of leading and trailing terminals. The right type depends on the lateral space available, whether there is a cut slope and the direction of traffic relative to the end of the run.
| Type | How it works | Key dimension |
|---|---|---|
| Turned-down terminal | Four guardrail modules drop from design height to a buried end, firmly anchored to the ground by a suitable terminal. | 4 modules |
| Turned-down terminal · slope | Angle between the top of the rails and the road surface. | ≤ 4°30′ · 1:12 |
| Energy-absorbing | In a head-on impact it absorbs the kinetic energy and brings the vehicle to a safe stop; in a side impact the anchorage develops tension and redirects. | — |
| Flared, anchored in a cut slope | The rails are flared horizontally to the cut slope, where they are firmly anchored. | — |
| Offset | Where there is relatively flat roadside, the guardrail starts away from the road, which reduces the length of need. | — |
| Trailing-end (downstream) | Two modules with gradual stiffening — second-to-last rail semi-rigid, last rail rigid — with a type A end piece. | 2 modules |
| Area in front of the terminal | The whole area in front of the terminal and between the road and the terminal. | max. 10H:1V |
| “—” = set by the design and the manufacturer’s specification. | ||
Sta. 04 · Site preparation
What must be ready before a terminal is installed?
Before the terminal is installed, the area in front of it and between the road and the terminal must have a maximum slope of 10H:1V. That is the condition for the terminal to perform as it was tested.
During installation, SinalServ checks this whole area: steeper ground changes the height and path at which the vehicle reaches the terminal. Nearby side slopes and gutters are also checked, since they can launch the vehicle over the restraint system.
For an offset terminal, the relatively flat roadside is precisely what allows the guardrail to start away from the road. For a flared terminal, the cut slope must provide firm anchorage for the end of the rails.
The guardrail between the two terminals follows the criteria described under metal guardrail installation.
Sta. 05 · Questions
Frequently asked questions about end terminals
The terminal starts and finishes the guardrail run safely. Without it, the end of the guardrail can spear the vehicle, vault it or roll it over in a head-on or angled impact. A guardrail run is only considered safe with suitable terminals at both ends.
A gating terminal lets a vehicle that hits it at an angle, on the nose or side before the beginning of length of need, pass through the unit. A non-gating terminal redirects the vehicle along its full length, from the impact head onwards. The classification follows NCHRP 350 and MASH criteria.
A turned-down terminal is made of four guardrail modules that drop from design height to a fully buried end anchored in the ground. The angle between the top of the rails and the road surface is at most 4°30′, about 1:12.
In a head-on impact, the energy-absorbing terminal dissipates the vehicle’s kinetic energy and brings it to a safe stop. In a side impact, the terminal anchorage develops tension in the guardrail and redirects the vehicle — from the length of need on gating terminals, and from the impact head on non-gating terminals.
The client specifies the device, based on the design. Leading and trailing terminals must meet the evaluation criteria of the applicable standards for the speed and impact angle of the stretch. SinalServ carries out the installation and checks the site conditions.
The whole area in front of the terminal, and between the road and the terminal, must have a maximum slope of 10H:1V, that is, no more than 1 m of fall for every 10 m horizontally. On steeper ground the vehicle reaches the terminal in a different position from the one tested.
Updated on
Sta. 06 · Quote
Request a quote for end terminals
Tell us how many runs and the terminal type in the design, if already defined. SinalServ checks the site conditions in the proposal.
We reply on the WhatsApp number or email you provide. The company tax ID routes your request to the right sales contact.