Each
year there arehundreds of incidents inwhich bridges are struck byvehicles
too high to passunder them. Both rail androad users have been killedin
these incidents. Look outfor signs in this section andmake sure
that you arenot a bridge basher.
All bridges with a clearance of less than 16 feet 6 inches (about5
metres) are normally signed. Both regulatory roundels andwarning
triangles can be used, depending on the type of bridge.
Bridges
particularly at risk from strikesmay have a variable message sign
thatis activated by high vehicles passingthrough an infra-red beam.
When thesign is activated, four amber lampsflash, the top pair alternating
with thebottom pair.
Regulatory
signs
No
vehiclesover the height shown may pass the sign (height shownin
metric and imperial units)
No
vehiclesover the height shown may pass the sign (height shownin
imperial units)
At
non-arch bridgesmandatory signs may beused; it is unlawful for
anoverheight vehicle to passone of these. They areplaced on the
bridge and atthe side of the road in frontof the bridge.
Advance
warning ofa mandatory height restriction ahead; the sign may
include an arrow, if the restriction is on a side road
Location
of mandatory height restriction ahead, with indication of
an alternative route
Warning signs
A
warning sign indicates, in imperial units, themaximum headroom under
a bridge or otheroverhead obstruction. There may be anadditional
sign showing the height in metricunits. These signs may be sited
well in advanceof a bridge, with the distance, either in yards ormiles,
shown on a plate; this may have anarrow to indicate that the bridge
is on a sideroad at a junction ahead.
Chord markings used indicate the points between which differentheadrooms
over different parts of an arch bridge are available.
The maximum safe headroom at an arch bridge is shown on thetriangular
warning signs. Road markings guide high vehiclesthrough the highest
part of the arch. Drivers of all vehicles shouldgive way to oncoming
high vehicles in the middle of the roadwhen there is insufficient
room to pass. Drivers of cars and otherlow vehicles may keep to the
left-hand side of the road, crossingthe road markings, where this
would enable them to passoncoming vehicles in safety
To improve the conspicuity of a bridge, black and yellow bandsmay
be added to the arches or beams and to the abutments.
Where
reduced headroom over a roadis due to an overhanging building
orstructure, a plate may be added below thewarning triangle to
indicate this ("building"may be varied to "buildings" or "structure").
Signs incorporating height restrictionroundels and
warning triangles
Roundels
or warning triangleswill sometimes be incorporatedinto directional
signs that mayalso indicate an alternative routeto take to avoid
the low bridge.
Roundels
may also beincorporated into road workssigns to indicate temporaryheight
restrictions.
