• Platform: The platform was first modified to meet only with my GPS traces. I walked on the edges of the platfofrm twice at an interval of a few hours. However, when you looked at other GPS traces of nearby roads and JR Takasaki line, it was apparently shifted northeast. Even a section was overlapped with the inbound track. Eventually, I aligned the position with nearby objects such as the station building and other GPS traces. It told me that GPS always has some degree of error even if it’s laid under an open sky. Just a few traces may not be enough to position a map feature.
• Station building: The shape of the station building was drawn based on Bing images and its position was aligned based on GPS data. On-site survey also helped greatly.
• Tracks: Train cars approach the platform very closely. This indicates the center of the track is apart from the platform edge half the width of the cars. The E231 series are currently used for Takasaki line whose width is 2.950 meters, which means the track is roughly 1.5 meters away from the platform edge.

Summary

Here’s a quick summary that I obtained through my acitivities to draw on the map the map features linked to JR Gyoda Station.

• Shape and angle: Bing images will surely help.
• Position (coordinate): As it’s often said, Bing may not provide an accurate position. Therefore, GPS should be used to locate the map feature. However, more than several traces may be needed because GPS has some degree of error even if it’s placed under good condition. It’s also important to look at GPS traces of nearly objects such as roads. It surely helps good alignment of the map feature. Sometimes, physical measurement of the length helps. I walk on the path and count my footsteps, which gives me a good estimate.