The narrow gauge railway and the creek both run under the tramway loop. No problem with the creek but the clearance for the steam locomotive is very tight with 1 mm between the the top of the funnel and the underside of the loop. This is too tight so something has to be done. Lowering the railway is not an option because of the risk of the creek flooding the line. Instead I will go for a thinner board under the tramway. Probably not quite right from an engineering perspective but it will not be visible once the sides of the future bridge are in place.