http://www.mha.gov.sg/news_details.aspx?nid=119
Combining satellite imagery from Google Earth and information released to the media, we can infer the probable location of the weak spot in the detention centre's security where the double fences converged with an enclosed walkway, and over which Mas Selamat is assumed to have climbed to escape from the centre. The infamous toilet is reported to have been 20 m from the enclosed walkway/fence, which would put it at the Southern end of the building, on the ground floor.
Google Earth placemark is at
http://tiny.cc/PnFbq
The Family Visitation Centre was apparently converted from former officers' quarters and was originally outside the boundaries of the detention center proper. Enclosed walkways between the cell blocks appear much wider and were presumably designed more securely. The walkway leading to the visitation centre is much smaller and was presumably added later, at the time that the building was converted to a visitation centre. Prior to that the building had been used as officers' quarters and administrative offices so would presumably not have required such high security.
Distance to Whitley Road from the breach point is 180 m straight line but 240 m via Onraet Road. This would be consistent with the distance that could be covered in 2 min 44 seconds as mentioned by WKS, but we cannot tell whether this really was the escape route taken by Mas Selamat.
