diff --git a/B05_Profile/B05_Profile_UI_Profile_CrossModal.css b/B05_Profile/B05_Profile_UI_Profile_CrossModal.css
index ee0e52e5a..b78246e7c 100644
--- a/B05_Profile/B05_Profile_UI_Profile_CrossModal.css
+++ b/B05_Profile/B05_Profile_UI_Profile_CrossModal.css
@@ -50,3 +50,54 @@
   justify-content: flex-end;
   gap: var(--spacing-8, 8px);
 }
+
+/* 임시 횡단이 열리는 자리 가까이 표시(490-1) — 누름은 아래 그래프 몫(통과) · 세로 축(5) 밑 */
+.b05-crosshint {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  left: 0;
+  z-index: 4;
+  width: 0;
+  pointer-events: none;
+}
+
+.b05-crosshint[hidden],
+.b05-crosshint__dot[hidden] {
+  display: none;
+}
+
+.b05-crosshint__line {
+  position: absolute;
+  top: 0;
+  bottom: 0;
+  left: 0;
+  border-left: 1px dashed var(--color-accent);
+}
+
+.b05-crosshint__dot {
+  position: absolute;
+  top: var(--crosshint-y);
+  left: 0;
+  width: 10px;
+  height: 10px;
+  border: 2px solid var(--color-accent);
+  border-radius: 50%;
+  background: var(--color-surface);
+  transform: translate(-50%, -50%);
+  box-sizing: border-box;
+}
+
+.b05-crosshint__label {
+  position: absolute;
+  top: var(--crosshint-y);
+  left: 10px;
+  transform: translateY(-50%);
+  padding: 1px 6px;
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-4, 4px);
+  background: var(--color-surface-raised);
+  color: var(--color-text-body);
+  font-size: var(--text-caption);
+  white-space: nowrap;
+}
diff --git a/B05_Profile/B05_Profile_UI_Profile_CrossModal.ts b/B05_Profile/B05_Profile_UI_Profile_CrossModal.ts
index 045bf2238..b89a16345 100644
--- a/B05_Profile/B05_Profile_UI_Profile_CrossModal.ts
+++ b/B05_Profile/B05_Profile_UI_Profile_CrossModal.ts
@@ -7,7 +7,7 @@
  * `pipelineCrossAtChainage` · 368-4) — 격자 없음 · 분석 지형 다름이면 서버 미리 뜬 횡단(`preview-stations` ·
  * 저장 계획선 기준 · 글 한 줄) · 평면 우측 횡단과 같은 그림(`buildCrossSvg`) · 확대 · 이동 · 묶음 cross 차례마다 다시.
  * [측점 추가] = 추가 측점 초안(일반측점 · [저장] 한 번) · 같은 m 에 측점이 있으면 막음 · [삭제] = 추가
- * 측점일 때만 · [닫기].
+ * 측점일 때만 · [닫기]. 열리는 자리 가까이 = 원 · 세로 점선 · 측점 글(`mountCrossHint` · 490-1).
  * ========================================================================== */
 
 import "./B05_Profile_UI_Profile_CrossModal.css";
@@ -30,9 +30,13 @@ import {
   CROSS_PLOT_PAD,
   summarizeCross,
 } from "./B05_Profile_UI_RouteEdit_Cross_Draw";
+import {
+  crossPickAt,
+  groundElevationAt,
+  type CrossPickHit,
+  type GroundSample,
+} from "./logic/B05_Profile_Profile_CrossPick";
 
-/** 원지반선을 눌렀다고 볼 위아래 여유(px). */
-const GROUND_SLACK_PX = 8;
 /** 같은 측점으로 볼 거리(m) — 정수 m 측점끼리. */
 const SAME_M = 0.5;
 
@@ -43,42 +47,87 @@ export interface CrossModalOpen {
   intervalM: number;
 }
 
-/** 그래프 누름 → 원지반선 근처면 그 누가거리(정수 m) · 아니면 null. */
-export function groundPickAt(
+/** 그래프 위 포인터 → 임시 횡단 자리(정수 m · 그 자리 원지반선 y px) · 아니면 null.
+ *  누름(작은 창) · 가까이 표시가 같이 씀(490-1) — 판정은 `crossPickAt` 한 벌. */
+export function crossPickFromEvent(
   chart: HTMLElement,
   event: MouseEvent,
   chainageAtPx: (px: number) => number,
-  samples: ReadonlyArray<{ chainage_m?: number; elevation_m?: number | null }>,
-): number | null {
+  samples: readonly GroundSample[],
+): { chainageM: number; groundY: number | null } | null {
+  const target = event.target as Element;
+  const marker = target.closest(".b06-chart__station");
+  const plusRaw = marker?.querySelector(".b06-chart__station-line--plus")
+    ? Number(marker.getAttribute("data-chainage"))
+    : null;
+  const hit: CrossPickHit =
+    plusRaw !== null ? { plusM: plusRaw } : marker || target.closest("button") ? "other" : null;
   const svg = chart.querySelector<SVGSVGElement>(`svg[${Y_WINDOW_ATTRS.auto}="1"]`);
-  if (!svg) return null;
-  const read = (name: string): number => Number(svg.getAttribute(name));
+  const read = (name: string): number => Number(svg?.getAttribute(name));
   const view: ChartWindow = {
     center: read(Y_WINDOW_ATTRS.center),
     pxPerM: read(Y_WINDOW_ATTRS.pxPerM),
     zero: read(Y_WINDOW_ATTRS.zero),
     ...parseWindowTransform(
-      svg.querySelector(`.${Y_WINDOW_CLASS}`)?.getAttribute("transform") ?? null,
+      svg?.querySelector(`.${Y_WINDOW_CLASS}`)?.getAttribute("transform") ?? null,
     ),
   };
-  if (![view.center, view.pxPerM, view.zero].every(Number.isFinite) || view.pxPerM <= 0)
-    return null;
   const rect = chart.getBoundingClientRect();
-  const chainage = chainageAtPx(event.clientX - rect.left);
-  const valid = samples.filter(
-    (s): s is { chainage_m: number; elevation_m: number } =>
-      Number.isFinite(s.chainage_m ?? NaN) && Number.isFinite(s.elevation_m ?? NaN),
-  );
-  const after = valid.findIndex((s) => s.chainage_m >= chainage);
-  if (!Number.isFinite(chainage) || after <= 0) return null;
-  const [a, b] = [valid[after - 1], valid[after]];
-  const t = (chainage - a.chainage_m) / (b.chainage_m - a.chainage_m || 1);
-  const ground = a.elevation_m + (b.elevation_m - a.elevation_m) * t;
-  const top = svg.getBoundingClientRect().top - rect.top;
-  const groundY = chartYAtElevation(view, ground) + top;
-  return Math.abs(event.clientY - rect.top - groundY) <= GROUND_SLACK_PX
-    ? Math.round(chainage)
-    : null;
+  const top = svg ? svg.getBoundingClientRect().top - rect.top : 0;
+  const viewOk =
+    !!svg && [view.center, view.pxPerM, view.zero].every(Number.isFinite) && view.pxPerM > 0;
+  const groundY = (elevation: number): number =>
+    viewOk ? chartYAtElevation(view, elevation) + top : NaN;
+  // 포인터 이동은 소수 px · 누름은 정수 px — 내려 맞춰 같은 자리 = 같은 m(0.5 m 경계에서 1 m 어긋남 막음).
+  const chainageM = crossPickAt({
+    hit,
+    chainageM: chainageAtPx(Math.floor(event.clientX) - rect.left),
+    pointerY: Math.floor(event.clientY) - rect.top,
+    samples,
+    groundY,
+  });
+  if (chainageM === null || !Number.isFinite(chainageM)) return null;
+  const ground = groundElevationAt(samples, chainageM);
+  const y = ground === null ? NaN : groundY(ground);
+  return { chainageM, groundY: Number.isFinite(y) ? y : null };
+}
+
+/** 임시 횡단이 열리는 자리 가까이 = 작은 원 · 세로 점선 · 측점 글 · 손가락 커서(490-1).
+ *  멀어짐 · 측점선 · 단추 · 도구 중 · 끌기 · 스크롤 = 안 그림. */
+export function mountCrossHint(
+  chart: HTMLElement,
+  scroller: HTMLElement,
+  options: {
+    pick: (event: MouseEvent) => { chainageM: number; groundY: number | null } | null;
+    x: (chainageM: number) => number;
+    intervalM: number;
+    blocked: () => boolean;
+  },
+): void {
+  const hint = document.createElement("div");
+  hint.className = "b05-crosshint";
+  hint.hidden = true;
+  hint.innerHTML = `<i class="b05-crosshint__line"></i><i class="b05-crosshint__dot"></i><span class="b05-crosshint__label"></span>`;
+  const dot = hint.querySelector<HTMLElement>(".b05-crosshint__dot")!;
+  const label = hint.querySelector<HTMLElement>(".b05-crosshint__label")!;
+  chart.append(hint);
+  const hide = (): void => {
+    hint.hidden = true;
+    chart.style.cursor = "";
+  };
+  chart.addEventListener("pointermove", (event) => {
+    const at = event.buttons || options.blocked() ? null : options.pick(event);
+    if (!at) return hide();
+    hint.hidden = false;
+    hint.style.left = `${options.x(at.chainageM)}px`;
+    dot.hidden = at.groundY === null;
+    // 원 · 글 높이 = 원지반선(없으면 위쪽) — 글이 위 ▲ 단추를 가리지 않게 원 옆에 둠.
+    hint.style.setProperty("--crosshint-y", `${at.groundY ?? 12}px`);
+    label.textContent = `${stationLabel(at.chainageM, options.intervalM)} · 눌러 임시 횡단`;
+    chart.style.cursor = "pointer";
+    scroller.addEventListener("scroll", hide, { once: true, passive: true });
+  });
+  chart.addEventListener("pointerleave", hide);
 }
 
 interface CrossModal {
diff --git a/B05_Profile/B05_Profile_UI_Profile_Render.ts b/B05_Profile/B05_Profile_UI_Profile_Render.ts
index 1e8fca7c4..5d8ece274 100644
--- a/B05_Profile/B05_Profile_UI_Profile_Render.ts
+++ b/B05_Profile/B05_Profile_UI_Profile_Render.ts
@@ -53,7 +53,8 @@ import {
 import { irregularStationId, type IrregularStation } from "./B05_Profile_UI_IrregularStations";
 import { mountStructureMenu } from "./B05_Profile_UI_Profile_Structures";
 import {
-  groundPickAt,
+  crossPickFromEvent,
+  mountCrossHint,
   openCrossModal,
   removePlusStation,
 } from "./B05_Profile_UI_Profile_CrossModal";
@@ -328,19 +329,11 @@ export function renderProfile(ctx: ProfileRenderContext): void {
     }
     // 원지반선 근처 · 추가 측점 선 누름 = 그 자리 임시 횡단 작은 창(368-3)
     //   다른 측점선 · 단추 누름은 그 몫(측점 고름 · ▲▼)
-    const target = event.target as Element;
-    const marker = target.closest(".b06-chart__station");
-    const plusAt = marker?.querySelector(".b06-chart__station-line--plus")
-      ? marker.getAttribute("data-chainage")
-      : null;
-    if ((marker && !plusAt) || target.closest("button")) return;
     const toChainageAt = chainageInverter(longitudinal, width, layout.originOffset);
-    const at = plusAt
-      ? Math.round(Number(plusAt))
-      : groundPickAt(chartWrap, event, toChainageAt, graphData.samples);
+    const at = crossPickFromEvent(chartWrap, event, toChainageAt, graphData.samples);
     if (at === null) return;
     openCrossModal(body.parentElement ?? body, {
-      chainageM: at,
+      chainageM: at.chainageM,
       stations: graphLongitudinal.stations.map((station) => station.chainage_m),
       intervalM: stationIntervalM ?? 20,
     });
@@ -495,6 +488,13 @@ export function renderProfile(ctx: ProfileRenderContext): void {
       }),
     );
   }
+  // 임시 횡단이 열리는 자리 가까이 = 원 · 세로 점선 · 측점 글(490-1 · 누름과 같은 판정).
+  mountCrossHint(chartWrap, body, {
+    pick: (event) => crossPickFromEvent(chartWrap, event, toChainage, graphData.samples),
+    x,
+    intervalM: stationIntervalM ?? 20,
+    blocked: ctx.toolActive,
+  });
   // 캔버스 높이 = 종단도 영역만. 서브패널이 차지한 아래 공간을 덮지 않는다(밀어올리기).
   // 구조물 알약 레인이 그래프 밑에 한 줄 붙으므로 그만큼 캔버스가 커진다(2026-08-17 지시 6).
   canvas.style.height = `${chartHeight + STRUCTURE_LANE_HEIGHT_PX}px`;
diff --git a/B05_Profile/logic/B05_Profile_Profile_CrossPick.ts b/B05_Profile/logic/B05_Profile_Profile_CrossPick.ts
new file mode 100644
index 000000000..1e51415c5
--- /dev/null
+++ b/B05_Profile/logic/B05_Profile_Profile_CrossPick.ts
@@ -0,0 +1,53 @@
+/* =============================================================================
+ * logic/B05_Profile_Profile_CrossPick.ts
+ * 종단 그래프 한 점 → 임시 횡단을 열 누가거리(정수 m) · 아니면 null(368-3 · 490-1).
+ *
+ * 누름(작은 창 열기)과 가까이 표시가 같은 판정을 씀 — 추가 측점 선 = 그 측점 · 다른 측점선 · 단추 =
+ * 그 몫(null) · 빈 곳 = 원지반선 위아래 `GROUND_SLACK_PX` 안.
+ * ========================================================================== */
+
+/** 원지반선을 눌렀다고 볼 위아래 여유(px). */
+export const GROUND_SLACK_PX = 8;
+
+/** 포인터 아래 = 추가 측점 선(그 누가거리) · 다른 측점선 · 단추("other") · 빈 곳(null). */
+export type CrossPickHit = { plusM: number } | "other" | null;
+
+export type GroundSample = { chainage_m?: number; elevation_m?: number | null };
+
+export interface CrossPickInput {
+  hit: CrossPickHit;
+  /** 포인터 x 의 누가거리. */
+  chainageM: number;
+  /** 포인터 y(그래프 px). */
+  pointerY: number;
+  samples: readonly GroundSample[];
+  /** 표고 → 그래프 y px(세로 창 없으면 NaN). */
+  groundY: (elevationM: number) => number;
+}
+
+/** 누가거리의 원지반 표고(앞뒤 표본 직선 보간) · 첫 표본 앞 · 끝 뒤 · 빈 표본 = null. */
+export function groundElevationAt(
+  samples: readonly GroundSample[],
+  chainageM: number,
+): number | null {
+  const valid = samples.filter(
+    (s): s is { chainage_m: number; elevation_m: number } =>
+      Number.isFinite(s.chainage_m ?? NaN) && Number.isFinite(s.elevation_m ?? NaN),
+  );
+  const after = valid.findIndex((s) => s.chainage_m >= chainageM);
+  if (!Number.isFinite(chainageM) || after <= 0) return null;
+  const [a, b] = [valid[after - 1], valid[after]];
+  const t = (chainageM - a.chainage_m) / (b.chainage_m - a.chainage_m || 1);
+  return a.elevation_m + (b.elevation_m - a.elevation_m) * t;
+}
+
+/** 임시 횡단을 열 누가거리(정수 m) · 아니면 null. */
+export function crossPickAt(input: CrossPickInput): number | null {
+  if (input.hit === "other") return null;
+  if (input.hit) return Math.round(input.hit.plusM);
+  const ground = groundElevationAt(input.samples, input.chainageM);
+  if (ground === null) return null;
+  return Math.abs(input.pointerY - input.groundY(ground)) <= GROUND_SLACK_PX
+    ? Math.round(input.chainageM)
+    : null;
+}
diff --git a/resources/tester/helper_490_1_cross_pick.cjs b/resources/tester/helper_490_1_cross_pick.cjs
new file mode 100644
index 000000000..52dc5abc2
--- /dev/null
+++ b/resources/tester/helper_490_1_cross_pick.cjs
@@ -0,0 +1,29 @@
+/* 490-1 임시 횡단 판정 — 진짜 `logic/B05_Profile_Profile_CrossPick.ts` 를 Node 로 돌려 냄.
+ * 입력 argv[2] JSON {samples, cases: [{hit, chainageM, pointerY}]} · groundY = 100 - 표고 × 2 px.
+ * 짝 = test_490_1_cross_pick.py. */
+const fs = require("fs");
+const path = require("path");
+const ts = require(path.join(__dirname, "..", "..", "config", "node_modules", "typescript"));
+
+const file = path.join(
+  __dirname,
+  "..",
+  "..",
+  "B05_Profile",
+  "logic",
+  "B05_Profile_Profile_CrossPick.ts",
+);
+const js = ts.transpileModule(fs.readFileSync(file, "utf8"), {
+  compilerOptions: { module: ts.ModuleKind.CommonJS, target: ts.ScriptTarget.ES2020 },
+}).outputText;
+const box = { exports: {} };
+new Function("exports", "module", "require", js)(box.exports, box, require);
+const logic = box.exports;
+
+const job = JSON.parse(fs.readFileSync(process.argv[2], "utf8"));
+const groundY = (elevation) => 100 - elevation * 2;
+const out = job.cases.map((c) => ({
+  pick: logic.crossPickAt({ ...c, samples: job.samples, groundY }),
+  ground: logic.groundElevationAt(job.samples, c.chainageM),
+}));
+process.stdout.write(JSON.stringify({ slack: logic.GROUND_SLACK_PX, out }));
diff --git a/resources/tester/test_368_3_cross_modal.py b/resources/tester/test_368_3_cross_modal.py
index 23b1f1a4e..3ea4faadc 100644
--- a/resources/tester/test_368_3_cross_modal.py
+++ b/resources/tester/test_368_3_cross_modal.py
@@ -24,7 +24,7 @@ def test_추가_측점_선_점선_끌기_없음() -> None:
 
 def test_누름_작은_창_우클릭_삭제() -> None:
     render = _read("B05_Profile/B05_Profile_UI_Profile_Render.ts")
-    assert "groundPickAt(chartWrap, event" in render and "openCrossModal(" in render
+    assert "crossPickFromEvent(chartWrap, event" in render and "openCrossModal(" in render
     assert "onRemovePlus: removePlusStation" in render
     menu = _read("B05_Profile/B05_Profile_UI_Profile_Structures.ts")
     assert '"측점 삭제", () => options.onRemovePlus?.(near.station.chainage_m)' in menu
diff --git a/resources/tester/test_490_1_cross_pick.py b/resources/tester/test_490_1_cross_pick.py
new file mode 100644
index 000000000..05d2c783d
--- /dev/null
+++ b/resources/tester/test_490_1_cross_pick.py
@@ -0,0 +1,87 @@
+"""490-1 B05 종단 — 임시 횡단이 열리는 자리 가까이 표시 = 누름과 같은 판정(`crossPickAt`).
+
+판정 함수 = 옛 누름 판정(원지반선 위아래 8 px · 정수 m · 추가 측점 선 = 그 측점 · 측점선 · 단추 = null)과
+같은 값 · 허용 밖 null. TS 쪽 = `helper_490_1_cross_pick.cjs`(Node). 화면 조작은 ORCA 로 확인.
+"""
+
+from __future__ import annotations
+
+import json
+import subprocess
+import tempfile
+from pathlib import Path
+
+HERE = Path(__file__).resolve().parent
+ROOT = HERE.parents[1]
+
+SAMPLES = [
+    {"chainage_m": 0.0, "elevation_m": 10.0},
+    {"chainage_m": 20.0, "elevation_m": 20.0},
+    {"chainage_m": 40.0, "elevation_m": None},  # 빈 표고는 건너뜀
+    {"chainage_m": 60.0, "elevation_m": 0.0},
+]
+
+
+def _ground_y(elevation: float) -> float:
+    return 100 - elevation * 2
+
+
+def _old_pick(hit, chainage: float, pointer_y: float) -> int | None:
+    """옛 `groundPickAt` + 누름 처리(Render.ts 329~346) 그대로."""
+    if hit == "other":
+        return None
+    if hit:
+        return round(hit["plusM"])
+    valid = [s for s in SAMPLES if s["elevation_m"] is not None]
+    after = next((i for i, s in enumerate(valid) if s["chainage_m"] >= chainage), -1)
+    if after <= 0:
+        return None
+    a, b = valid[after - 1], valid[after]
+    t = (chainage - a["chainage_m"]) / (b["chainage_m"] - a["chainage_m"] or 1)
+    ground = a["elevation_m"] + (b["elevation_m"] - a["elevation_m"]) * t
+    return round(chainage) if abs(pointer_y - _ground_y(ground)) <= 8 else None
+
+
+CASES = [
+    {"hit": None, "chainageM": 10.2, "pointerY": 69.8},  # 지반 y = 69.8 · 딱 위
+    {"hit": None, "chainageM": 10.2, "pointerY": 77.8},  # 8 px 끝
+    {"hit": None, "chainageM": 10.2, "pointerY": 78.3},  # 허용 밖
+    {"hit": None, "chainageM": 10.2, "pointerY": 61.3},  # 위쪽 허용 밖
+    {"hit": None, "chainageM": 50.0, "pointerY": 93.0},  # 빈 표고 건너 20→60 보간
+    {"hit": None, "chainageM": 0.0, "pointerY": 80.0},  # 첫 표본 = null(옛 판정 그대로)
+    {"hit": None, "chainageM": 70.0, "pointerY": 100.0},  # 끝 뒤
+    {"hit": {"plusM": 33.6}, "chainageM": 10.0, "pointerY": 0.0},  # 추가 측점 선
+    {"hit": "other", "chainageM": 10.4, "pointerY": 70.0},  # 측점선 · 단추
+]
+
+
+def _run() -> dict:
+    with tempfile.TemporaryDirectory() as folder:
+        path = Path(folder) / "job.json"
+        path.write_text(json.dumps({"samples": SAMPLES, "cases": CASES}), encoding="utf-8")
+        proc = subprocess.run(  # noqa: S603 — 고정 실행 파일
+            ["node", str(HERE / "helper_490_1_cross_pick.cjs"), str(path)],
+            capture_output=True,
+            text=True,
+            encoding="utf-8",
+            timeout=60,
+        )
+    assert proc.returncode == 0, proc.stderr
+    return json.loads(proc.stdout)
+
+
+def test_판정_함수_옛_누름과_같은_값() -> None:
+    result = _run()
+    assert result["slack"] == 8
+    picks = [row["pick"] for row in result["out"]]
+    assert picks == [_old_pick(c["hit"], c["chainageM"], c["pointerY"]) for c in CASES]
+    assert picks == [10, 10, None, None, 50, None, None, 34, None]
+
+
+def test_누름_표시_같은_길() -> None:
+    render = (ROOT / "B05_Profile/B05_Profile_UI_Profile_Render.ts").read_text(encoding="utf-8")
+    assert render.count("crossPickFromEvent(chartWrap, event") == 2  # 누름 · 표시
+    assert "mountCrossHint(chartWrap, body" in render and "blocked: ctx.toolActive" in render
+    modal = (ROOT / "B05_Profile/B05_Profile_UI_Profile_CrossModal.ts").read_text(encoding="utf-8")
+    assert "crossPickAt({" in modal and "event.buttons || options.blocked()" in modal
+    assert 'scroller.addEventListener("scroll", hide' in modal