Highway & DOT Drainage

Drainage by Application

Roadway trench drains, toll plazas, rest areas, weigh stations, and maintenance yards all answer to a DOT specification — and to traffic that never stops coming. The systems below are the ones we quote most for state and municipal roadway work.

What roadway drainage has to survive

Highway drainage takes repeated wheel impacts at speed, thermal cycling, snowplow blades, and deicing salt — simultaneously. Grates that rattle in their frames pound themselves loose lane-mile by lane-mile; unsecured grates on high-speed alignments are a genuine safety failure, which is why DOT specs demand positive locking. The hydraulics are unforgiving too: superelevation transitions and sag curves concentrate sheet flow exactly where standing water is most dangerous, so the drain has to intercept flow across the full lane width and move it fast. Winter climates add freeze-thaw attack on the channel body itself. All of it has to be maintainable from the surface without closing a lane for a day.

Load class guidance

In or beside a travel lane, Class D (400 kN) is the usual floor. Where trucks brake, queue, or turn hard — toll booths, weigh stations, depot gates — step up to Class E (600 kN) or Class F (900 kN). The load class recommendation guide maps all six EN 1433 classes to typical placements; the governing DOT spec always has the final word.

Recommended systems

Extra heavy duty rated trench drain grate under vehicular traffic

Travel lanes, toll plazas, weigh stations

ACO PowerDrain S100K / S200K / S300K

Polymer concrete channels with integrally cast ductile iron edge rails and published loading to EN 1433 Class F as a complete system. Numbered channels build a 0.5% slope into the run; ductile iron grates with locking hardware stay put under braking traffic. Available in 4-, 8-, and 12-inch internal widths to match catchment and flow.

Freeze-thaw climates, medians, roadside hardscape

BG Filcoten Trench Drains

Channels cast from fiber-reinforced high-performance concrete that stands up to frost, temperature swings, and UV exposure without cracking or early wear — and bonds naturally with the surrounding concrete encasement. Sloped-channel layouts run up to 135 feet with a center catch basin, or 162 feet combining sloped and neutral channels. See the Filcoten FAQs & resources for series details.

Rest areas, park-and-rides, facility surrounds

ACO KlassikDrain

The modular polymer-concrete workhorse for the lower-speed paved areas around highway facilities, from the 4-inch K100 to the 12-inch K300, with galvanized or stainless edge rails and a deep grate catalog. Load classification varies by grate and model — we confirm each component at quote.

Grate & casting replacement on existing inlets

Replacement Grates & Foundry Castings

For rehab and maintenance contracts we supply ductile iron and cast iron replacement grates plus municipal castings from EJ and U.S. Foundry. Send frame dimensions and we will match the casting.

Josam Pro Plus polymer concrete trench drainage is also available on request for roadway and infrastructure projects.

Planning resources

Load Class Recommendation Guide — EN 1433 classes A–F with typical placements
Sizing for Storms: Estimating Runoff — sizing runs for design-storm flows
Runoff Calculator — quick catchment math for paved corridors
Filcoten Trench Drain FAQs & Resources

Highway drainage FAQs

What load class do DOT and highway trench drains require?

Under EN 1433 classes, drainage in or immediately alongside a travel lane is generally Class D (400 kN) duty at minimum, and locations with concentrated slow-moving truck traffic — toll plazas, weigh stations, maintenance yards — are commonly specified at Class E or F. Always confirm the governing DOT specification for the project; grate, channel, and installation detail must be approved together.

Can you match an existing DOT inlet grate or frame casting?

Usually, yes. We supply municipal and highway castings from EJ and U.S. Foundry along with a full range of replacement metal grates. Send the frame's clear opening, seat dimensions, and duty rating — or a photo with a tape measure — and we will identify a compatible casting and quote it.

How long can a highway trench drain run before it needs an outlet?

It depends on rainfall intensity, catchment width, and channel capacity, not just channel length. Pre-sloped channel systems build fall into the run itself; catch basins placed mid-run split long runs into manageable hydraulic sections. Start with our runoff estimating guide and calculator, then send us the layout for a system takeoff.