I think the lorry crane operator is solely at fault, which is
why the police arrested the bangladeshi as reported on TV. The
following are possible safety lapses from the lorry operator and
company:
1) The boom of the crane must not protrude onto the path of
vehicles at all times; because the lorry company, supervisor and
crane operator have a duty of care to ensure safety at all times.
This is under the MOM Occupation Safety and Health Act and I
believe the crane operator and company will be investigated and
probably prosecuted by MOM.
2) If the boom is necessary to be extended, then the supervisor
in-charge got to place cones and signages to the front or back of
the lorry to block the affected lane so that vehicles will avoid
hitting the crane. And the boom must not protrude onto the adjacent
lanes where vehicles are free to move at all times.
3) Did the lorry company station a person as a look-out for any
safety lapses when the crane is in operation? Solely depending on
the crane operator is not the solution to ensure safety to the
public and motorists.
4) I think SBST and the victims can claim the lorry company's
insurance company and it is mandatory for contractors to purchase
insurance policies for every project they undertake.
Although I'm not a driver and dont really know the conduct of
the tree cutting operators, but I agree the point that the boom
should not obstruct any area beyond it's cordoned area so to say,
since they are working without road closure at any rate.
Since there are multiple workers among the tree cutting ops, I
thought one of them ought to be a "road martial" who only gotta
signal and redirect drivers and maybe need not do other stuff? At
any rate, if the crane is lowering, there's a call in advance and
that signaller will proceed to control traffic.
The tree cutting squad has been there before the
bus came, so at any rate the tree cutting squad is at more liberty
of look out the traffic and do any action like traffic control
or pause operation if i may say so. For the BC, even if
he stop behind the truck and dont overtake, he might end up
blocking the mouth of the zebra crossing and who knows,
the boom might swivel into windscreen all the same than a full
row swipe as it did.
In short, the truck is doing stationary work while traffic
beside continue to flow, so to say they are at more liberty in
controlling the boom and to direct the traffic than a bus who dont
really foresee wat is ahead of its road.
I'm not a pro, pls pardon my ignorance if any and dont flame me
if that's so. 
