In construction work at urban intersections, construction barriers can severely obstruct the view of right-turning vehicles, thereby posing safety hazards and increasing delays. Taking the intersection of Nanhu Avenue and Dongling South Street in Changchun City as an example, this paper innovatively proposes relocating the right-turn lane to the left, merging the right-turn traffic flow into the left-turn phase, and implementing dynamic left-turn relocation strategies for vehicles turning left in the opposite direction to separate traffic flows. This study provides detailed channelization design schemes for relocating the right-turn lane to the left and merging the left- and right-turn lanes. To optimize traffic efficiency and environmental benefits, a multi-objective signal timing optimization model was constructed to minimize the total intersection delay, maximize traffic capacity, and minimize carbon emissions. The model was analyzed using the non-dominated genetic algorithm (NSGA-II) to determine the effective green light duration for each phase, the pre-signal control scheme, and the length of the dynamically shifted left-turn lane, followed by VISSIM traffic simulation. The results show that compared with the traditional intersection, the optimized design reduced the delay for straight-through vehicles at the north entrance from 118 s to 21 s (a decrease of 82%). The delays for all phases at the south entrance decreased by 20–50%, and delays for straight and left-turn vehicles at the west and east entrances also decreased. The overall total delay decreased from 53.3 s to 41.1 s (a 23% reduction), validating the effectiveness and applicability of the method and model proposed in this work.