Why do double decker buses around the uk have bars on the upper front of the buses????

Perhaps they're something to grab hold, so's you don't go @$$ over tea kettle, when the bus makes a sudden stop?

They're actually known as "Tree catchers" and are intended to rip off any overhanging tree branches they might encounter. This has become necessary now since councils find it too expensive to keep trees properly lopped on bus routes, and the bus companies say it's not their job, so the good old poke your nose in - oh sorry - Health and Safety people have demanded that these be fitted to prevent upper deck front windows being smashed.

Yeah, its to stop the windscreen from being damaged from trees. And so if the bus hits anything it abosorbs the inpact and protects the front of the bus

If the bus has an emergency stop ,people at the front don't shoot out of windows

Externally to stop branches hitting the window,internally to help you to get up from the front seat,also to stop you from going through the widdow in case of accident

to stop you going through the front window and from things coming in like low bridges, branches etc.

they put the bars on the upper deck to discourage the driver from drinking and driving

Its needed depending on the bus driver's state of mind....

so if the bus crashes, you have something to hold on to and have less chance of flying out the window

Its to prevent overhanging branches to hit the window