It's called pork barrel politics folks. The NDP is trying to solidify those Surrey, lower Fraser Valley ridings by doing the voters there a favor (as they promised during the election, and one of the main reasons they did well there). 

And the costs will then be foisted on to the rest of BC residents through higher taxes, so everyone can pay. The NDP doesn't care if people in Northern BC, who never or rarely use these bridges have to pay for them - because they know they'll never win any significant number of ridings beyond Hope. The NDP is clearly just a party of and for the Lower Mainland/ Van Island, which is pretty sad for the rest of the province.