How to Modify an Existing Road to Bridge                                      Edit an article
by  Srinivas                                    

In Short

Learn to convert the road drawn above the bridge section, to Bridge through few magic edits.


In many cases, The road drawn above the bridge is drawn at a single stretch which make the process of converting the road to bridge, a tedious one. This article describes how to convert the road section to bridge in a simple manner especially for new users.


The main aim is to change the Elevation attribute of the road from Normal to Bridge in the road segment above the bridge. This leads to two cases,

Case 1: Length of the road segment above the bridge is same as the length of the bridge.

Case 2: Length of the road segment above the bridge is lengthier than the bridge.

In first case, one can just select the road segment and change its Elevation attribute from Normal to Bridge. Here is a link to help article on how to edit a road segment.

In case two, when the Road segment is lengthier than the Bridge, an artificial intersection has to be created, so that the length of the Road segment above the Bridge are equal in length with the Bridge.

Creating an Artificial Intersection

An intersection is created when a road is intersected by another road. So the next step would be creating an intersection by intersecting the road segment at the exact points where the bridge ends. This can be done by following these simple steps:

  1. Draw two perpendicular roads at both ends of the bridge, which will segregate the road segment with the newly formed intersections. These are sometimes called "dummy roads." 

  2. Select the segment that represents the bridge and click on edit this segment change the Elevation attribute from Normal to Bridge as we did in Case 1 above.

  3. Delete the newly drawn "dummy roads."


Points to Remember

Use comments to inform the reviewer that you are using dummy roads to create the intersections. You can mention this when drawing, editing, and deleting your segments to help keep your hard work from getting denied for seeming obscure.

The above steps can be followed to convert a Road to Tunnel or Skyway depending upon the requirement.

Tips and Tricks

For new users: Delete the dummy roads last, after changing the elevation attribute of the bridge section. This is done to ensure deleting the dummy road does not put a hold on your progress, waiting for a review.

While splitting a road using dummy segments, just draw them out to one side of the road, like a T rather than an X. So that you only have 2 segments to delete.

When making edits in GMM, you may find your progress hindered by the need for approval. For these situations, you can post your review request in Review edits request ForumHere, pending edits are brought to the attention of local mappers and reviewers.

This dummy road procedure can also be used for adding traffic signs to a segment such as railway crossing and Do Not Enter signs. Learn more about adding traffic signs to an intersection here.


The main idea for creating this article is taken from the How to draw a bridge on a existing roads thread from the General Map Maker Forum and the credits goes to all the Mapper who poured their thoughts in the thread.