Trap Bridge problem

Hi, I have a small issue with a custom trap bridge block I found. It works really well most of the time, but if I build horizontal bridges with it zombies will still be able to climb it as shown on the video. It doesn't happen with vertical bridges, just horizontals. Any idea of how to fix it?



Here's the code of the bridge itself, as far as I know it's based on a normal trap block.

Spoiler: a

Code:

// TrapBridge.as

#include "Hitters.as";
#include "MapFlags.as";
#include "DoorCommon.as";

int openRecursion = 0;

bool oldTrapBehaviour(CBlob@ this)
{
    return getRules().hasTag("old trap blocks");
}

void onInit(CBlob@ this)
{
    this.getShape().SetRotationsAllowed(false);

    this.set_bool("open", false);
    this.Tag("place norotate");

    //block knight sword
    this.Tag("blocks sword");
    this.Tag("blocks water");

    this.set_TileType("background tile", CMap::tile_castle_back);

    MakeDamageFrame(this);
    this.getCurrentScript().runFlags |= Script::tick_not_attached;
    this.getCurrentScript().tickFrequency = 0;
}

void onTick(CBlob@ this)
{
    bool touching = false;
    const uint count = this.getTouchingCount();
    for(uint step = 0; step < count; ++step)
    {
        CBlob@ blob = this.getTouchingByIndex(step);
        if(opensThis(this, blob))
        {
            setOpen(this, true);
            this.getShape().checkCollisionsAgain = true;
        }
    }
}

void onSetStatic(CBlob@ this, const bool isStatic)
{
    CSprite@ sprite = this.getSprite();
    if(sprite is null) return;

    sprite.getConsts().accurateLighting = true;

    if(!isStatic) return;

    this.getSprite().PlaySound("/build_wood.ogg");
}

void onHealthChange(CBlob@ this, f32 oldHealth)
{
    if(!isOpen(this))
    {
        MakeDamageFrame(this);
    }
}

void MakeDamageFrame(CBlob@ this)
{
    f32 hp = this.getHealth();
    f32 full_hp = this.getInitialHealth();
    int frame = (hp > full_hp * 0.9f) ? 0 : ((hp > full_hp * 0.4f) ? 1 : 2);
    this.getSprite().animation.frame = frame;
}

bool isOpen(CBlob@ this)
{
    return !this.getShape().getConsts().collidable;
}

void setOpen(CBlob@ this, bool open)
{
    CSprite@ sprite = this.getSprite();

    if(open)
    {
        sprite.SetZ(-100.0f);
        sprite.animation.frame = 3;
        this.getShape().getConsts().collidable = false;
        this.getShape().checkCollisionsAgain = true;
    }
    else
    {
        sprite.SetZ(100.0f);
        MakeDamageFrame(this);
        this.getShape().getConsts().collidable = true;
    }

    //TODO: fix flags sync and hitting
    //SetSolidFlag(this, !open);

    if(this.getTouchingCount() <= 1 && openRecursion < 5)
    {
        SetBlockAbove(this, open);
        openRecursion++;
    }
}

bool doesCollideWithBlob(CBlob@ this, CBlob@ blob)
{
    if(!opensThis(this, blob))
    {
        return !isOpen(this);
    }
    else
    {
        return !opensThis(this, blob) && !isOpen(this);
    }
}

bool opensThis(CBlob@ this, CBlob@ blob)
{
    return !oldTrapBehaviour(this) && canOpenDoor(this, blob) || //allow teamies to use it like a door
            (blob.getTeamNum() != this.getTeamNum() &&
            !isOpen(this) && blob.isCollidable() &&
            (blob.hasTag("zombie") || blob.hasTag("player") || blob.hasTag("vehicle")));
}

bool mightOpenThis(CBlob@ this, CBlob@ blob)
{
    return !oldTrapBehaviour(this) && (this.getTeamNum() == blob.getTeamNum());
}

void onCollision(CBlob@ this, CBlob@ blob, bool solid)
{
    if(blob is null) return;

    if(opensThis(this, blob))
    {
        openRecursion = 0;
        setOpen(this, true);
    }
    else if(mightOpenThis(this, blob))
    {
        this.getCurrentScript().tickFrequency = 1;
    }
}

void onEndCollision(CBlob@ this, CBlob@ blob)
{
    if(blob is null) return;

    bool touching = false;
    const uint count = this.getTouchingCount();
    for(uint step = 0; step < count; ++step)
    {
        CBlob@ blob = this.getTouchingByIndex(step);
        if(blob.isCollidable())
        {
            touching = true;
            break;
        }
    }

    if(!touching)
    {
        setOpen(this, false);
        this.getCurrentScript().tickFrequency = 0;
    }
}

bool canBePickedUp(CBlob@ this, CBlob@ byBlob)
{
    return false;
}

void SetBlockAbove(CBlob@ this, const bool open)
{
    CBlob@ blobAbove = getMap().getBlobAtPosition(this.getPosition() + Vec2f(0, -8));
    if(blobAbove is null || blobAbove.getName() != "trap_bridge") return;

    setOpen(blobAbove, open);
}

(Here are the files for the bridge, I still don't know how to upload them in the post)
http://puu.sh/pP9uW/eb7082e663.7z