Bridgetown, Barbados – Oct.
9, 2007 -- The Barbados Association of Professional Engineers (BAPE) has
already expressed concerns about the ABC
Highway expansion project being undertaken by 3S
Structural Solutions LLC.
These
concerns include:
• the
contract was agreed without a competitive tender process;
• the
flyover solution was agreed before a traffic study was done; and this study was then
undertaken by the same firm whose flyover proposal had already been accepted;
• the
approval process for a project requiring such a large investment of public
funds should
have included a rigorous technical and economic feasibility study.
In
addition to the company’s financial position, the qualification of a contractor
to undertake this project
should also have included consideration of the qualifications and experience of
the key personnel,
the nature of the contractor’s past experience, and a review of the firm’s
litigation history.
Having
observed the work in progress, BAPE questions whether full consideration has
been given to
the following areas which could negatively impact public safety and maintenance
costs.
1.
The drainage design at the superelevated sections (i.e. banked corners) of the
highway between
Wildey and Warrens appears to violate major road drainage engineering design principles.
At superelevated sections, the entire width of the highway slopes in one direction,
and rainwater would similarly drain in the same one direction. The design being
built includes elongated horizontal slots near the base of the concrete medians
to allow
water to drain from the northbound lanes to the southbound lanes and vice
versa.
During
a recent period of heavy rainfall, it was observed that the volume of water
flowing as
a sheet across the southbound section was very significant. The danger is that
this water
could lead to hydroplaning, a loss of traction between vehicle tires and the
road, and
the loss of control of the vehicle, resulting in serious accidents. One of the
worst possible
locations to lose control of a vehicle is in a corner. To reduce the risk of hydroplaning,
technical standards used in highway design provide recommended limits on
the volume of sheet flow. Other problems associated with inadequate drainage
are a potential
reduction in the durability of the pavement surface and an increase in the splatter
of water, which also has the potential to lead to vehicle accidents.
• BAPE
recommends that 3S be asked to provide information on the standards used
in the design of this road drainage system, and to identify where in the world
they have constructed a similar road drainage design, so that the consequential
effects can be examined.
2.
Another safety concern is the location of the concrete islands at the Belle
intersection. The
islands are built along the continuation of the highway curb line, which on a
highway such
as this, means that they could present a collision danger to road users. It
would be advisable
that these be set back a minimum of 2 feet.
• BAPE
recommends that 3S be asked to provide information on the standards used
in the design of this intersection, and examples of similarly constructed intersections
they have designed elsewhere so that the consequential effects can be
examined.
3.
Based on observations of the spacing between street lighting fixtures it
appears that fullcutoff fixtures
rather than the previous semi-cutoff fixtures will be used. Full-cutoff fixtures
put light on the ground below the fixture only, and do not emit light above 90
degrees. There is therefore less “uplight” and light pollution from the
fixture.
This
is desirable, however to achieve uniform lighting either more fixtures must
be
used or the height must be increased – both of which have cost and energy use implications. Additionally,
the lighting pole bases appear to be unusually small, raising concerns over the
design wind speeds employed.
