Safety campaigners have expressed disbelief over Transport for London (TfL) proposals to remove a footbridge, near the St Margarets roundabout.
TfL plans include removing the bridge, which stands over the A316 Chertsey Road, and installation a new toucan crossing instead.
It claimed the new system would improve road use for cyclists but campaigners, including parents at close-by St Stephen's Primary, said it was a "disaster waiting to happen".
Campaigner Caroline Bond said: "This area has a very large density of young families and children and there are three schools - St Stephens, Orleans and Orleans Park - which use this as a main route.
"A consequence of changing to a traffic light operated system is the traffic will be pretty much stopped from 8.15am to 9am with children permanently crossing the road to get to school, and again in the afternoon.
"The knock-on effect to the traffic congestion in the area will be horrendous - it will be backed up all the way to Richmond Circus and all the way through St Margarets and beyond.
"I could understand this bridge being removed if it was not used but if anyone comes in the morning and afternoon and see the huge volume of people that use it every day, it is pure madness to take it down.
"This is a disaster waiting to happen, and there will be young people casualties on that road if this goes ahead."
TfL is running a consultation period with residents until July 4 and said a toucan crossing would make life easier for cyclists using the main road.
On its website, it said: "To make full use of the new toucan crossing, we propose to remove the cycle lane markings from the footway and create shared pedestrian/cycle space.
"This would allow cyclists that use the new toucan crossing facility to continue along the footway either side of the crossing without having to dismount.
"The toucan crossing would improve accessibility for everyone - all roads on this roundabout would then have accessible crossing points."
But St Margarets mother Julia Farish, 41, who uses the crossing with her two children, would not feel safe crossing the busy road.
The Ailsa Avenue resident said: "Everyone goes over the bridge as half the catchment area for St Stephen's is north St Margarets.
"I would no longer feel safe crossing that road with my children.
"A toucan crossing would lead to too many people waiting in the middle - it doesn't make sense."
To respond to TfL's survey, visit consultations.tfl.gov.uk/consultation-and-engagement/a316-st-margarets-crossing.