src/main/java/com/conveyal/gtfs/GTFSFeed.java
public Geometry getMergedBuffers() {
        if (this.mergedBuffers == null) {
//            synchronized (this) {
                Collection<Geometry> polygons = new ArrayList<>();
                for (Stop stop : this.stops.values()) {
                    if (getStopTimesForStop(stop.stop_id).isEmpty()) {
                        continue;
                    }
                    if (stop.stop_lat > -1 && stop.stop_lat < 1 || stop.stop_lon > -1 && stop.stop_lon < 1) {
                        continue;
                    }
                    Point stopPoint = gf.createPoint(new Coordinate(stop.stop_lon, stop.stop_lat));
                    Polygon stopBuffer = (Polygon) stopPoint.buffer(.01);
                    polygons.add(stopBuffer);
                }
                Geometry multiGeometry = gf.buildGeometry(polygons);
                this.mergedBuffers = multiGeometry.union();
                if (polygons.size() > 100) {
                    this.mergedBuffers = DouglasPeuckerSimplifier.simplify(this.mergedBuffers, .001);
                }
//            }
        }
        return this.mergedBuffers;
    }
public Geometry getMergedBuffers() {
        if (this.mergedBuffers == null) {
//            synchronized (this) {
                Collection<Geometry> polygons = new ArrayList<>();
                for (Stop stop : this.stops.values()) {
                    if (getStopTimesForStop(stop.stop_id).isEmpty()) {
                        continue;
                    }
                    if (stop.stop_lat > -1 && stop.stop_lat < 1 || stop.stop_lon > -1 && stop.stop_lon < 1) {
                        continue;
                    }
                    Point stopPoint = gf.createPoint(new Coordinate(stop.stop_lon, stop.stop_lat));
                    Polygon stopBuffer = (Polygon) stopPoint.buffer(.01);
                    polygons.add(stopBuffer);
                }
                Geometry multiGeometry = gf.buildGeometry(polygons);
                this.mergedBuffers = multiGeometry.union();
                if (polygons.size() > 100) {
                    this.mergedBuffers = DouglasPeuckerSimplifier.simplify(this.mergedBuffers, .001);
                }
//            }
        }
        return this.mergedBuffers;
    }
TODO: code review